Journal of the Mechanical Behavior of Biomedical Materials最新文献_第3页

Collagen content and crosslinks alter the biomechanical properties of corneal tissues 胶原蛋白含量和交联改变了角膜组织的生物力学特性。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-13 DOI: 10.1016/j.jmbbm.2025.107276

Anshul Shrivastava , Yogesh Thapliyal , Subhradeep Sarkar , Arkasubhra Ghosh , Namrata Gundiah

Lamellar and dispersed fibrous collagen networks are organized and maintained via endogenous crosslinks along the superior-inferior and nasal-temporal directions in the stromal regions of corneal tissues. Collagen organization contributes to corneal transparency, tissue integrity, and the surface topography. Ultrastructural changes to the lamellar arrangement of collagen occur in diseases, such as keratoconus and ectasia post refractive surgery, resulting in impaired biomechanical properties, changes to the surface curvature, and irregular astigmatism. Collagen crosslinking with UV-A/riboflavin is used clinically to increase the structural integrity and halt corneal thinning; however it can cause complications in certain cases. Earlier studies suggest that crosslinking mediated by advanced glycation end products (AGE), associated with ageing, may increase corneal stiffness and prevent corneal thinning. The specific links between corneal properties and microstructural network features are however not well established. We used collagenase and non-enzymatic crosslinking using methylglyoxal (MGO) to investigate the effects of collagen content, organization, and crosslinking densities in an ex-vivo goat cornea model. We estimated the collagen contents using a biochemical assay, performed uniaxial mechanical tests, and used histology to quantify the underlying fiber tortuosity in untreated (control) and collagenase/MGO treated groups. We fit the experimental stress-strain data using an exponential strain energy function (SEF) that uses a generalized structure tensor to describe collagen fiber organization in tissues. Our results show that fiber tortuosity increased with collagenase treatment time. AGE-mediated non-enzymatic crosslinking using MGO caused a dramatic increase in the elastic modulus of tissues without significant changes to the fiber tortuosity or overall collagen content. Finally, we obtained scaling relationships linking tissue modulus to collagen volume fraction that may be useful clinically. Changes in fiber tortuosity with collagenase treatment suggest that collagen fiber organization and composition play a key role in regulating mechanobiological properties of the cornea.

层状和分散的纤维胶原网络是通过角膜组织间质区沿上-下和鼻-颞方向的内源性交联组织和维持的。胶原组织有助于角膜透明度、组织完整性和表面形貌。屈光手术后圆锥角膜和角膜扩张等疾病会导致胶原板层排列的超微结构改变，从而导致生物力学特性受损、表面曲率改变和不规则散光。胶原与UV-A/核黄素交联在临床上用于增加结构完整性和阻止角膜变薄；然而，在某些情况下，它会引起并发症。早期的研究表明，与衰老相关的晚期糖基化终产物（AGE）介导的交联可能增加角膜僵硬并防止角膜变薄。然而，角膜特性与微观结构网络特征之间的具体联系尚未很好地建立。我们使用胶原酶和使用甲基乙二醛（MGO）的非酶交联来研究离体山羊角膜模型中胶原含量、组织和交联密度的影响。我们使用生化分析来估计胶原含量，进行单轴力学测试，并使用组织学来量化未治疗组（对照组）和胶原酶/MGO治疗组的潜在纤维扭曲程度。我们使用指数应变能函数（SEF）拟合实验应力-应变数据，该函数使用广义结构张量来描述组织中的胶原纤维组织。结果表明，纤维弯曲度随胶原酶处理时间的延长而增加。使用MGO介导的年龄介导的非酶交联引起组织弹性模量的显着增加，而纤维弯曲度或总体胶原蛋白含量没有显着变化。最后，我们获得了组织模量与胶原体积分数之间的比例关系，这可能在临床上有用。胶原酶治疗后纤维扭曲的变化表明，胶原纤维的组织和组成在调节角膜的力学生物学特性中起关键作用。

{"title":"Collagen content and crosslinks alter the biomechanical properties of corneal tissues","authors":"Anshul Shrivastava , Yogesh Thapliyal , Subhradeep Sarkar , Arkasubhra Ghosh , Namrata Gundiah","doi":"10.1016/j.jmbbm.2025.107276","DOIUrl":"10.1016/j.jmbbm.2025.107276","url":null,"abstract":"<div><div>Lamellar and dispersed fibrous collagen networks are organized and maintained <em>via</em> endogenous crosslinks along the superior-inferior and nasal-temporal directions in the stromal regions of corneal tissues. Collagen organization contributes to corneal transparency, tissue integrity, and the surface topography. Ultrastructural changes to the lamellar arrangement of collagen occur in diseases, such as keratoconus and ectasia post refractive surgery, resulting in impaired biomechanical properties, changes to the surface curvature, and irregular astigmatism. Collagen crosslinking with UV-A/riboflavin is used clinically to increase the structural integrity and halt corneal thinning; however it can cause complications in certain cases. Earlier studies suggest that crosslinking mediated by advanced glycation end products (AGE), associated with ageing, may increase corneal stiffness and prevent corneal thinning. The specific links between corneal properties and microstructural network features are however not well established. We used collagenase and non-enzymatic crosslinking using methylglyoxal (MGO) to investigate the effects of collagen content, organization, and crosslinking densities in an <em>ex-vivo</em> goat cornea model. We estimated the collagen contents using a biochemical assay, performed uniaxial mechanical tests, and used histology to quantify the underlying fiber tortuosity in untreated (control) and collagenase/MGO treated groups. We fit the experimental stress-strain data using an exponential strain energy function (SEF) that uses a generalized structure tensor to describe collagen fiber organization in tissues. Our results show that fiber tortuosity increased with collagenase treatment time. AGE-mediated non-enzymatic crosslinking using MGO caused a dramatic increase in the elastic modulus of tissues without significant changes to the fiber tortuosity or overall collagen content. Finally, we obtained scaling relationships linking tissue modulus to collagen volume fraction that may be useful clinically. Changes in fiber tortuosity with collagenase treatment suggest that collagen fiber organization and composition play a key role in regulating mechanobiological properties of the cornea.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107276"},"PeriodicalIF":3.5,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145552403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ex-vivo biomechanical characterization of porcine cava vein 猪腔静脉的离体生物力学特征

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-13 DOI: 10.1016/j.jmbbm.2025.107271

Eleonora Luzietti , Martina Schembri , Ariel F. Pascaner , Ferdinando Auricchio , Alessandro Caimi , Michele Conti

In recent years, percutaneous procedures are gradually replacing open heart surgery for the treatment of tricuspid valve pathological conditions deploying prosthetic devices (i.e., stent-graft) within the proximal portion of the cava veins. Nevertheless, since there is no comprehensive mechanical characterization of the venous district, the devices exploited in these procedures are very similar to the ones exploited in aortic treatment, involving possible critical periprocedural complications.

According to the international standards adopted for the design of novel vascular devices, this study presents an experimental set-up to investigate the biomechanics of fifteen porcine cava veins with the development of a semi-automatic protocol for compliance testing. During the tests, 2D echo images of the vessel lumen are acquired for different steps within a pressure range of 5–20 mmHg. The acquired pressure-diameter curves of the samples are then derived by a polynomial function, furthermore, the compliance values are obtained using the corresponding equations as well.

The results demonstrate that the cava vein exhibits a hyperelastic behavior, with a nonlinear relationship between pressure and diameter. At low pressures, the veins demonstrate high compliance and reduced stiffness (11.54 ± 4.76 kPa). On the contrary, when pressures exceed the normal physiological range (i.e., greater than 10 mmHg), the veins become stiffer (294.70 ± 233.00 kPa).

The developed set-up, based on an ex-vivo porcine model, proved to be a robust tool for the assessment of vein biomechanics and for preclinical benchmarking of novel venous endovascular devices.

近年来，经皮手术逐渐取代心内直视手术治疗三尖瓣病状，在腔静脉近端植入假体装置（即支架移植）。然而，由于没有全面的静脉区力学特征，这些手术中使用的设备与主动脉治疗中使用的设备非常相似，可能涉及严重的围手术期并发症。根据新型血管装置设计的国际标准，本研究建立了一个实验装置，研究了15条猪腔静脉的生物力学，并开发了一种半自动的顺应性测试方案。在测试过程中，在5-20 mmHg的压力范围内，通过不同的步骤获得血管腔的二维回声图像。然后用多项式函数推导得到试样的压力-直径曲线，并利用相应的方程求出柔度值。结果表明，腔静脉具有超弹性，压力与直径呈非线性关系。在低压下，矿脉表现出较高的顺应性和较低的刚度（11.54±4.76 kPa）。相反，当压力超过正常生理范围（即大于10mmhg）时，静脉变硬（294.70±233.00 kPa）。基于离体猪模型的开发装置被证明是静脉生物力学评估和新型静脉血管内装置临床前基准测试的强大工具。

{"title":"Ex-vivo biomechanical characterization of porcine cava vein","authors":"Eleonora Luzietti , Martina Schembri , Ariel F. Pascaner , Ferdinando Auricchio , Alessandro Caimi , Michele Conti","doi":"10.1016/j.jmbbm.2025.107271","DOIUrl":"10.1016/j.jmbbm.2025.107271","url":null,"abstract":"<div><div>In recent years, percutaneous procedures are gradually replacing open heart surgery for the treatment of tricuspid valve pathological conditions deploying prosthetic devices (<em>i.e., stent</em>-<em>graft)</em> within the proximal portion of the cava veins. Nevertheless, since there is no comprehensive mechanical characterization of the venous district, the devices exploited in these procedures are very similar to the ones exploited in aortic treatment, involving possible critical periprocedural complications.</div><div>According to the international standards adopted for the design of novel vascular devices, this study presents an experimental set-up to investigate the biomechanics of fifteen porcine cava veins with the development of a semi-automatic protocol for compliance testing. During the tests, 2D echo images of the vessel lumen are acquired for different steps within a pressure range of 5–20 mmHg. The acquired pressure-diameter curves of the samples are then derived by a polynomial function, furthermore, the compliance values are obtained using the corresponding equations as well.</div><div>The results demonstrate that the cava vein exhibits a hyperelastic behavior, with a nonlinear relationship between pressure and diameter. At low pressures, the veins demonstrate high compliance and reduced stiffness (11.54 ± 4.76 kPa). On the contrary, when pressures exceed the normal physiological range (<em>i.e.,</em> greater than 10 mmHg), the veins become stiffer (294.70 ± 233.00 kPa).</div><div>The developed set-up, based on an <em>ex-vivo</em> porcine model, proved to be a robust tool for the assessment of vein biomechanics and for preclinical benchmarking of novel venous endovascular devices.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107271"},"PeriodicalIF":3.5,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145615176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evaluation of a universal talus implant during gait: a combined musculoskeletal and finite element modelling approach 评估通用距骨植入在步态：联合肌肉骨骼和有限元建模方法。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-13 DOI: 10.1016/j.jmbbm.2025.107278

Sami Al Shweiki , Stephen J. Ferguson , Ahmed H. Hafez , Naod T. Mogos , Tao Liu , Marwan El-Rich

Universal talus implant has emerged as an innovative solution for talus bone collapse, aiming to retain the clinical benefits of custom total talus replacement while addressing its logistical drawbacks. A subject-specific combined musculoskeletal–finite element (MSK–FE) modeling framework was developed to evaluate two universal talus implant designs during dynamic gait: a purely cobalt chromium (CoCr) implant, and an implant coated with polycarbonate-urethane (PCU), both compared to the native talus. To do so, a MSK simulation of the stance phase of gait was conducted to estimate joint kinematics and joint reaction forces in the ankle complex, with a subsequent dynamic FE simulation performed to assess contact characteristics in terms of contact area and pressure, in cartilages surrounding the talus/implant. The FE model was built directly from the bone geometries of the MSK model to ensure consistency across the study. Results showed that the PCU-coated implant more closely replicated native biomechanics, while the CoCr implant produced consistently higher pressures and smaller contact regions. Normalized RMSE across gait confirmed lower deviation from the native case for the PCU-implant in most joints. These findings highlight the potential of PCU coated implants in improving contact mechanics in articular cartilage as well as the potential of the universal implant topology. This is the first study to dynamically evaluate intra-articular behaviour in all joints surrounding the talus bone during gait, and particularly by analysing the performance of universal talus implants, demonstrating the utility of a MSK-FE approach and offering valuable insights into implant performance under physiological conditions, informing future implant design.

通用距骨植入物作为距骨塌陷的创新解决方案，旨在保留自定义全距骨置换术的临床益处，同时解决其物流缺陷。开发了一种受试者特异性联合肌肉骨骼-有限元（MSK-FE）建模框架，以评估动态步态期间两种通用距骨植入设计：纯钴铬（CoCr）植入物和涂有聚碳酸酯-聚氨酯（PCU）的植入物，两者都与天然距骨进行了比较。为此，对步态的站立阶段进行MSK模拟，以估计踝关节复合体的关节运动学和关节反作用力，随后进行动态有限元模拟，以评估距骨/植入物周围软骨的接触面积和压力方面的接触特性。有限元模型是直接从MSK模型的骨几何形状建立的，以确保整个研究的一致性。结果表明，pcu包覆种植体更接近于原始生物力学，而CoCr种植体持续产生更高的压力和更小的接触区域。步态的标准化RMSE证实，大多数关节的pci -implant与本地病例的偏差较小。这些发现突出了PCU涂层植入物在改善关节软骨接触力学方面的潜力，以及通用植入物拓扑结构的潜力。这是第一个动态评估步态中距骨周围所有关节内行为的研究，特别是通过分析通用距骨植入物的性能，证明了MSK-FE方法的实用性，并为生理条件下植入物的性能提供了有价值的见解，为未来的植入物设计提供了信息。

{"title":"Evaluation of a universal talus implant during gait: a combined musculoskeletal and finite element modelling approach","authors":"Sami Al Shweiki , Stephen J. Ferguson , Ahmed H. Hafez , Naod T. Mogos , Tao Liu , Marwan El-Rich","doi":"10.1016/j.jmbbm.2025.107278","DOIUrl":"10.1016/j.jmbbm.2025.107278","url":null,"abstract":"<div><div>Universal talus implant has emerged as an innovative solution for talus bone collapse, aiming to retain the clinical benefits of custom total talus replacement while addressing its logistical drawbacks. A subject-specific combined musculoskeletal–finite element (MSK–FE) modeling framework was developed to evaluate two universal talus implant designs during dynamic gait: a purely cobalt chromium (CoCr) implant, and an implant coated with polycarbonate-urethane (PCU), both compared to the native talus. To do so, a MSK simulation of the stance phase of gait was conducted to estimate joint kinematics and joint reaction forces in the ankle complex, with a subsequent dynamic FE simulation performed to assess contact characteristics in terms of contact area and pressure, in cartilages surrounding the talus/implant. The FE model was built directly from the bone geometries of the MSK model to ensure consistency across the study. Results showed that the PCU-coated implant more closely replicated native biomechanics, while the CoCr implant produced consistently higher pressures and smaller contact regions. Normalized RMSE across gait confirmed lower deviation from the native case for the PCU-implant in most joints. These findings highlight the potential of PCU coated implants in improving contact mechanics in articular cartilage as well as the potential of the universal implant topology. This is the first study to dynamically evaluate intra-articular behaviour in all joints surrounding the talus bone during gait, and particularly by analysing the performance of universal talus implants, demonstrating the utility of a MSK-FE approach and offering valuable insights into implant performance under physiological conditions, informing future implant design.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107278"},"PeriodicalIF":3.5,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145566908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical analysis of sutural tessellations under dynamic indentation 动态压痕下缝线镶嵌的数值分析

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-12 DOI: 10.1016/j.jmbbm.2025.107270

Richard J. Nash, Yaning Li

Sudden dynamic loading scenarios can often lead to undesirable mechanical responses in certain systems. However, in nature it is seen that certain species are found to have biological sutures in regions of their body where they are accustomed to dynamic loading. This has inspired the implementation of sutural geometries into originally flat regular hexagonal honeycomb tessellation interfaces comprised of harder hexagonal phases joined by a thinner, softer phase. These sutures are characterized by their tooth tip angle, wavelength, and amplitude and are studied to determine their influences the mechanical responses of the samples under dynamic indentation loading. Interestingly, suture tessellations can achieve negative Poisson's ratio in a certain design space. Both auxetic and non-auxetic designs under dynamic indentation loadings have been investigated via finite element (FE) simulations. Dynamic explicit FE simulations are conducted, using elasto-perfectly-plastic models for both hard and soft phases. The introduction of suture geometry leads to less plastic deformation in the composites, better dispersion of impact energy, and a lower peak load compared to the original flat tessellation counterparts. Additionally, results show that for 2D sutural tessellations, auxeticity enhances energy dissipation efficiency under dynamic indentation load.

在某些系统中，突然的动态加载场景通常会导致不期望的机械响应。然而，在自然界中，我们发现某些物种在它们习惯于动态负荷的身体部位有生物缝合线。这激发了将缝合线几何形状应用于原本平坦的规则六边形蜂窝镶嵌界面的灵感，该界面由较硬的六边形相和较薄、较软的相组成。研究了这些缝合线的针尖角度、波长和振幅，并确定了它们在动态压痕载荷下对样品力学响应的影响。有趣的是，缝合镶嵌可以在一定的设计空间内实现负泊松比。通过有限元模拟研究了动态压痕载荷下的消声和非消声设计。采用弹塑性模型对软、硬两阶段进行了显式动态有限元模拟。与原始的平面镶嵌材料相比，缝线几何结构的引入减少了复合材料的塑性变形，更好地分散了冲击能量，并且峰值载荷更低。此外，研究结果还表明，在动态压痕荷载作用下，二维缝合线镶嵌的互补性提高了能量耗散效率。

{"title":"Numerical analysis of sutural tessellations under dynamic indentation","authors":"Richard J. Nash, Yaning Li","doi":"10.1016/j.jmbbm.2025.107270","DOIUrl":"10.1016/j.jmbbm.2025.107270","url":null,"abstract":"<div><div>Sudden dynamic loading scenarios can often lead to undesirable mechanical responses in certain systems. However, in nature it is seen that certain species are found to have biological sutures in regions of their body where they are accustomed to dynamic loading. This has inspired the implementation of sutural geometries into originally flat regular hexagonal honeycomb tessellation interfaces comprised of harder hexagonal phases joined by a thinner, softer phase. These sutures are characterized by their tooth tip angle, wavelength, and amplitude and are studied to determine their influences the mechanical responses of the samples under dynamic indentation loading. Interestingly, suture tessellations can achieve negative Poisson's ratio in a certain design space. Both auxetic and non-auxetic designs under dynamic indentation loadings have been investigated via finite element (FE) simulations. Dynamic explicit FE simulations are conducted, using elasto-perfectly-plastic models for both hard and soft phases. The introduction of suture geometry leads to less plastic deformation in the composites, better dispersion of impact energy, and a lower peak load compared to the original flat tessellation counterparts. Additionally, results show that for 2D sutural tessellations, auxeticity enhances energy dissipation efficiency under dynamic indentation load.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107270"},"PeriodicalIF":3.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The influence of infrapatellar fat pad resection on knee joint friction and damping: An in vitro study in New Zealand white rabbits 髌下脂肪垫切除对新西兰大白兔膝关节摩擦和阻尼影响的体外研究

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-12 DOI: 10.1016/j.jmbbm.2025.107257

Will J. Clayton , Davis R. Ballard , Amelia J. Strozier , Maryam F. Afzali , Kelly S. Santangelo , John L. Williams

The infrapatellar fat pad (IFP), an adipose tissue located in the anterior knee joint, is hypothesized to absorb shocks and aid in joint lubrication. We investigated the consequences of IFP removal on joint friction and damping in an in vitro animal model. The hindlimbs of female New Zealand white rabbits were dissected to retain the knee ligaments, joint capsule, and patellar retinaculum. Knees were mounted in a pendulum with the knee joint serving as the fulcrum while keeping the quadriceps tendon unloaded to assess joint friction and damping in each knee for three conditions: Control, Sham, and no IFP (IFP-R). Friction and damping were assessed under a 15N tibio-femoral joint load (40 % of body weight) at three flexion angles (50°, 100°, and 130°), and gyroscopic data were recorded to obtain the time decay of amplitude. Two models, a linear friction and an exponential decay friction model, were fit to the amplitude decay over time. The linear model provided Stanton's joint boundary friction coefficient (μ_L); the exponential decay model provided an exponential decay friction (μ_E) and a viscous damping (c) coefficient. When compared across all angles of testing, IFP removal decreased μ_L by 6 % (p = 0.0057) vs Controls (μ_L = 0.0217 vs 0.0230); IFP removal decreased c by 9 % (p < 0.001) vs Controls (c = 0.00262 vs 0.00239 kgm²/s) and by 6 % vs Sham (p = 0.017, c = 0.00255 vs 0.00239 kgm²/s). IFP removal did not affect μ_E (p = 0.12).

髌下脂肪垫（IFP）是一种位于膝关节前部的脂肪组织，被认为可以吸收冲击并帮助关节润滑。我们在体外动物模型中研究了IFP去除对关节摩擦和阻尼的影响。解剖雌性新西兰大白兔后肢，保留膝关节韧带、关节囊和髌骨支持带。在三种情况下：对照组、假手术和无IFP (IFP- r)，双膝以膝关节为支点，保持股四头肌肌腱卸载，以评估每个膝关节的关节摩擦和阻尼。在三个屈曲角度（50°，100°和130°）下，在15N的胫骨-股骨关节载荷（体重的40% %）下评估摩擦和阻尼，并记录陀螺仪数据以获得振幅的时间衰减。两个模型，线性摩擦和指数衰减摩擦模型，适合振幅衰减随时间的变化。线性模型给出了斯坦顿节理边界摩擦系数（μL）；指数衰减模型给出了指数衰减摩擦系数μE和粘性阻尼系数c。在所有测试角度进行比较时，与对照组（μL = 0.0217 vs 0.0230）相比，IFP去除率降低了6 μL % (p = 0.0057)；奖学金项目删除c降低了9 % (p & lt; 0.001)和控制(c = 0.00262 vs 0.00239 kgm2 / s)和6 % vs骗局(p = 0.017 c = 0.00255 vs 0.00239 kgm2 / s)。去除IFP对μE无影响（p = 0.12）。

{"title":"The influence of infrapatellar fat pad resection on knee joint friction and damping: An in vitro study in New Zealand white rabbits","authors":"Will J. Clayton , Davis R. Ballard , Amelia J. Strozier , Maryam F. Afzali , Kelly S. Santangelo , John L. Williams","doi":"10.1016/j.jmbbm.2025.107257","DOIUrl":"10.1016/j.jmbbm.2025.107257","url":null,"abstract":"<div><div>The infrapatellar fat pad (IFP), an adipose tissue located in the anterior knee joint, is hypothesized to absorb shocks and aid in joint lubrication. We investigated the consequences of IFP removal on joint friction and damping in an in vitro animal model. The hindlimbs of female New Zealand white rabbits were dissected to retain the knee ligaments, joint capsule, and patellar retinaculum. Knees were mounted in a pendulum with the knee joint serving as the fulcrum while keeping the quadriceps tendon unloaded to assess joint friction and damping in each knee for three conditions: Control, Sham, and no IFP (IFP-R). Friction and damping were assessed under a 15N tibio-femoral joint load (40 % of body weight) at three flexion angles (50°, 100°, and 130°), and gyroscopic data were recorded to obtain the time decay of amplitude. Two models, a linear friction and an exponential decay friction model, were fit to the amplitude decay over time. The linear model provided Stanton's joint boundary friction coefficient (μ<sub>L</sub>); the exponential decay model provided an exponential decay friction (μ<sub>E</sub>) and a viscous damping (c) coefficient. When compared across all angles of testing, IFP removal decreased μ<sub>L</sub> by 6 % (p = 0.0057) vs Controls (μ<sub>L</sub> = 0.0217 vs 0.0230); IFP removal decreased c by 9 % (p < 0.001) vs Controls (c = 0.00262 vs 0.00239 kgm<sup>2</sup>/s) and by 6 % vs Sham (p = 0.017, c = 0.00255 vs 0.00239 kgm<sup>2</sup>/s). IFP removal did not affect μ<sub>E</sub> (p = 0.12).</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107257"},"PeriodicalIF":3.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Negative and positive Poynting effects in tendon under simple shear 单纯剪切作用下肌腱的负、正坡印亭效应。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-12 DOI: 10.1016/j.jmbbm.2025.107268

C.S. Moreira , F.S. Araújo , L.C.S. Nunes

Shear load transfer is crucial for the redistribution of internal tendon loads and to prevent excessive local stress that can lead to severe damage and injury. To better understand this transfer mechanism, it is important to know the stress state. The aim of the present study is to investigate the normal and shear stresses in tendons sheared with the shear force applied parallel to the fascicles and collagen fibers. A key novelty of the paper is the simultaneous measurement of normal and shear forces, as well as the amount of shear of tendon samples under simple shear. For the sake of simplicity, a more straightforward model is employed to describe the normal and shear behavior of tendons. Expressions were simultaneously fitted to the measured normal and shear stresses. The results reveal that the shear behavior did not exhibit any evidence of strain-stiffening, because the shear stress was approximately proportional to the amount of shear. However, compressive and tensile normal stresses, or positive and negative Poynting effects, respectively, were observed in different samples. Each tendon specimen was sheared along the orientation of the longitudinal fascicles and collagen fibers, which were maintained by random fiber networks associated with connective tissue and cross-link structures. Compressive normal stress indicates that random fiber networks did not influence the behavior or were not significant in a certain range, whereas random fiber networks contribution was more pronounced in the case of tensile normal stress. These findings suggest that the effects of random fiber networks, which can manifest over different length scales, play an important role in the state of normal stress in tendons under simple shear. Understanding how random fiber networks influence tendon mechanics could lead to better treatments for tendon injuries and help design biomimetic materials.

剪切载荷转移对于内部肌腱载荷的重新分配和防止可能导致严重损伤和损伤的过度局部应力至关重要。为了更好地理解这种传递机制，了解应力状态是很重要的。本研究的目的是研究平行于筋束和胶原纤维的剪切力对肌腱的法向应力和剪应力的影响。本文的一个关键新颖之处在于同时测量法向力和剪力，以及单剪下肌腱样品的剪切量。为了简单起见，采用了一个更直接的模型来描述肌腱的法向和剪切行为。表达式同时拟合测量的法向应力和剪应力。结果表明，由于剪切应力与剪切量近似成正比，剪切行为没有表现出应变硬化的迹象。然而，在不同的样品中分别观察到压应力和拉应力，或正坡印亭效应和负坡印亭效应。每个肌腱标本沿着纵向束和胶原纤维的方向剪切，胶原纤维由与结缔组织和交联结构相关的随机纤维网络维持。压缩法向应力表明随机纤维网络在一定范围内不影响或不显著，而在拉伸法向应力情况下，随机纤维网络的贡献更为明显。这些发现表明，随机纤维网络的影响，可以在不同的长度尺度上表现出来，在单剪下肌腱的正常应力状态中起重要作用。了解随机纤维网络如何影响肌腱力学，可以更好地治疗肌腱损伤，并有助于设计仿生材料。

{"title":"Negative and positive Poynting effects in tendon under simple shear","authors":"C.S. Moreira , F.S. Araújo , L.C.S. Nunes","doi":"10.1016/j.jmbbm.2025.107268","DOIUrl":"10.1016/j.jmbbm.2025.107268","url":null,"abstract":"<div><div>Shear load transfer is crucial for the redistribution of internal tendon loads and to prevent excessive local stress that can lead to severe damage and injury. To better understand this transfer mechanism, it is important to know the stress state. The aim of the present study is to investigate the normal and shear stresses in tendons sheared with the shear force applied parallel to the fascicles and collagen fibers. A key novelty of the paper is the simultaneous measurement of normal and shear forces, as well as the amount of shear of tendon samples under simple shear. For the sake of simplicity, a more straightforward model is employed to describe the normal and shear behavior of tendons. Expressions were simultaneously fitted to the measured normal and shear stresses. The results reveal that the shear behavior did not exhibit any evidence of strain-stiffening, because the shear stress was approximately proportional to the amount of shear. However, compressive and tensile normal stresses, or positive and negative Poynting effects, respectively, were observed in different samples. Each tendon specimen was sheared along the orientation of the longitudinal fascicles and collagen fibers, which were maintained by random fiber networks associated with connective tissue and cross-link structures. Compressive normal stress indicates that random fiber networks did not influence the behavior or were not significant in a certain range, whereas random fiber networks contribution was more pronounced in the case of tensile normal stress. These findings suggest that the effects of random fiber networks, which can manifest over different length scales, play an important role in the state of normal stress in tendons under simple shear. Understanding how random fiber networks influence tendon mechanics could lead to better treatments for tendon injuries and help design biomimetic materials.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107268"},"PeriodicalIF":3.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145552451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A virtual model for the osteosynthesis fixation strength analysis of cancellous screws considering the insertion effect in sawbones with experimental validation 考虑锯骨插入效应的松质螺钉接骨固定强度分析虚拟模型，并经实验验证。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-11 DOI: 10.1016/j.jmbbm.2025.107267

James Wu , Xuan Hu , David Benoit , Franck Le Navéaux , Julien Clin , Shaofan Li , Reno Genest , Ram Gopisetti , Bo Ren

Although the finite element method (FEM) is a valuable computational tool for analyzing factors that influence bone–screw fixation strength in osteosynthesis, it faces challenges in capturing the effects of screw insertion prior to pullout simulation due to mesh distortion and element erosion. To address these limitations, this study introduces an orthopedic computational model based on the Smoothed Particle Galerkin (SPG) method, offering an enhanced approach for simulating bone–screw interactions.

The Smoothed Particle Galerkin (SPG) method is an advanced mesh-free numerical technique capable of simulating large deformations and material removal while avoiding common mesh-related issues in FEM. In this study, the SPG method is used to model the Sawbones material during screw insertion and pullout. A bond-failure model is incorporated into the SPG framework to represent material removal, employing two failure criteria: the critical effective shear strain and the critical effective plastic strain. This modeling approach allows for accurate reproduction of thread formation in the bone during screw insertion, capturing the appropriate contact geometry and residual stress conditions for subsequent pullout simulations.

To validate the accuracy of the proposed simulation model, experimental tests were performed using Sawbones specimens composed of grade 15 PCF polyurethane foam, serving as an analog for human cancellous bone. The nonlinear material properties of the Sawbones were characterized following ASTM D1621 for compression and ASTM D1623 for tension. Parameters of the bond-failure model were calibrated through a combined screw insertion and pullout simulation using a non-fluted screw with a pilot hole. For the predictive analysis, three test cases were modeled, each combining different pilot-hole sizes and screw types, with and without cutting flutes.

The proposed simulation model successfully reproduces thread formation, a feature that is difficult to capture using conventional FEM approaches. The results demonstrate that screw insertion induces residual stress, which strongly affects the pullout force. In addition, both pilot-hole size and screw design are shown to significantly influence residual stress and pullout performance. Comparison of pullout forces between experiments and simulations across three prediction cases, showing average errors of +4.0 %, −11.8 %, and −6.0 %, indicates that the proposed model is a promising tool for analyzing bone–screw fixation strength while accounting for the screw insertion effect, a capability not available in existing simulation frameworks.

虽然有限元方法（FEM）是一种有价值的计算工具，用于分析影响骨螺钉固定强度的因素，但由于网格畸变和单元侵蚀，它面临着在拔出模拟之前捕获螺钉插入影响的挑战。为了解决这些局限性，本研究引入了一种基于光滑粒子伽erkin （SPG）方法的骨科计算模型，为模拟骨-螺钉相互作用提供了一种增强的方法。光滑粒子伽辽金（SPG）方法是一种先进的无网格数值模拟技术，能够模拟大变形和材料去除，同时避免了有限元中常见的网格相关问题。在本研究中，SPG方法用于模拟螺钉插入和拔出过程中的Sawbones材料。采用临界有效剪切应变和临界有效塑性应变两种破坏准则，将粘结破坏模型纳入SPG框架中，以表示材料的去除。这种建模方法可以精确再现螺钉插入过程中骨内螺纹的形成，为随后的拔出模拟捕获适当的接触几何形状和残余应力条件。为了验证所提出的模拟模型的准确性，使用由15级PCF聚氨酯泡沫组成的Sawbones样品进行了实验测试，作为人类松质骨的模拟物。锯骨的非线性材料特性按照ASTM D1621的压缩和ASTM D1623的张力进行表征。通过使用带导孔的无槽螺钉插入和拔出组合模拟，校准了粘结破坏模型的参数。为了进行预测分析，对三个测试用例进行了建模，每个测试用例都结合了不同的导孔尺寸和螺杆类型，有和没有切削槽。提出的仿真模型成功地再现了螺纹形成，这是传统FEM方法难以捕捉的特征。结果表明，螺杆插入会产生残余应力，对拉拔力有较大影响。此外，导孔尺寸和螺杆设计对残余应力和拉拔性能都有显著影响。在三种预测情况下，实验和模拟的拔出力对比显示，平均误差为+ 4.0%,- 11.8%和- 6.0%，表明所提出的模型是一种很有前景的工具，可以分析骨螺钉固定强度，同时考虑螺钉插入效应，这是现有模拟框架所不具备的能力。

{"title":"A virtual model for the osteosynthesis fixation strength analysis of cancellous screws considering the insertion effect in sawbones with experimental validation","authors":"James Wu , Xuan Hu , David Benoit , Franck Le Navéaux , Julien Clin , Shaofan Li , Reno Genest , Ram Gopisetti , Bo Ren","doi":"10.1016/j.jmbbm.2025.107267","DOIUrl":"10.1016/j.jmbbm.2025.107267","url":null,"abstract":"<div><div>Although the finite element method (FEM) is a valuable computational tool for analyzing factors that influence bone–screw fixation strength in osteosynthesis, it faces challenges in capturing the effects of screw insertion prior to pullout simulation due to mesh distortion and element erosion. To address these limitations, this study introduces an orthopedic computational model based on the Smoothed Particle Galerkin (SPG) method, offering an enhanced approach for simulating bone–screw interactions.</div><div>The Smoothed Particle Galerkin (SPG) method is an advanced mesh-free numerical technique capable of simulating large deformations and material removal while avoiding common mesh-related issues in FEM. In this study, the SPG method is used to model the Sawbones material during screw insertion and pullout. A bond-failure model is incorporated into the SPG framework to represent material removal, employing two failure criteria: the critical effective shear strain and the critical effective plastic strain. This modeling approach allows for accurate reproduction of thread formation in the bone during screw insertion, capturing the appropriate contact geometry and residual stress conditions for subsequent pullout simulations.</div><div>To validate the accuracy of the proposed simulation model, experimental tests were performed using Sawbones specimens composed of grade 15 PCF polyurethane foam, serving as an analog for human cancellous bone. The nonlinear material properties of the Sawbones were characterized following ASTM <span><span>D1621</span><svg><path></path></svg></span> for compression and ASTM <span><span>D1623</span><svg><path></path></svg></span> for tension. Parameters of the bond-failure model were calibrated through a combined screw insertion and pullout simulation using a non-fluted screw with a pilot hole. For the predictive analysis, three test cases were modeled, each combining different pilot-hole sizes and screw types, with and without cutting flutes.</div><div>The proposed simulation model successfully reproduces thread formation, a feature that is difficult to capture using conventional FEM approaches. The results demonstrate that screw insertion induces residual stress, which strongly affects the pullout force. In addition, both pilot-hole size and screw design are shown to significantly influence residual stress and pullout performance. Comparison of pullout forces between experiments and simulations across three prediction cases, showing average errors of +4.0 %, −11.8 %, and −6.0 %, indicates that the proposed model is a promising tool for analyzing bone–screw fixation strength while accounting for the screw insertion effect, a capability not available in existing simulation frameworks.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107267"},"PeriodicalIF":3.5,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of stent-graft length and compliance on aortic hemodynamics in a bench-top physiological flow circuit 支架长度和顺应性对台式生理血流回路主动脉血流动力学的影响

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-11 DOI: 10.1016/j.jmbbm.2025.107269

Ramin Shahbad, Elizabeth Zermeno, Sayed Ahmadreza Razian, Kaspars Maleckis, Majid Jadidi, Anastasia Desyatova

The aortic elasticity plays a vital role in buffering pulsatile blood flow, propelling blood to distal organs and the heart, and reducing cardiac workload. Aortic repair with a stent-graft can reduce this elasticity and hinder the aorta's ability to effectively perform its function. Conventional stent-grafts are associated with increased arterial stiffness, elevated pulse wave velocity (PWV), and adverse hemodynamic changes. This is largely driven by stiffness mismatch between the stent-graft and the native aortic wall, which alters mechanical compliance and hemodynamic response. This study evaluates a novel compliant nanofiber stent-graft (NF-SG) developed to closely mimic native aortic mechanics. Using a bench-top physiological flow circuit, we assessed the hemodynamic impacts of stent-graft stiffness and length on arterial parameters, including PWV, pulse pressure (PP), and distensibility in vitro, and compared these effects with conventional stent-grafts. Stent-graft stiffness significantly affected PWV, PP, and distensibility. Conventional stent-grafts showed 14 %–52 % increase in PWV depending on stent-graft length (p < 0.001), 5 %–32 % increase in PP, and 82 % reduction in mid-graft distensibility. In contrast, NF-SGs maintained PWV and PP near baseline levels with marginal effect of the stent-graft length. Distensibility in the mid-graft was reduced by 13 %–20 %, depending on the stent-graft length. The NF-SG's superior compliance and reduced hemodynamic perturbation were attributed to its mechanically optimized fabric and skeleton design. These findings underscore the clinical potential of the compliant stent-grafts to significantly mitigate long-term cardiovascular complications and preserve aortic functionality post-intervention.

主动脉弹性在缓冲搏动血流、推动血液流向远端器官和心脏、减少心脏负荷等方面起着至关重要的作用。主动脉支架移植修复会降低这种弹性，阻碍主动脉有效发挥其功能。常规支架移植物与动脉僵硬度增加、脉波速度（PWV）升高和不利的血流动力学改变有关。这在很大程度上是由支架移植物与原生主动脉壁之间的刚度不匹配引起的，这改变了机械顺应性和血流动力学反应。这项研究评估了一种新型柔顺纳米纤维支架移植物（NF-SG）的发展，以密切模仿天然主动脉力学。使用台式生理血流回路，我们评估了支架移植刚度和长度对动脉参数的血流动力学影响，包括PWV、脉压（PP）和体外扩张性，并将这些影响与传统支架移植进行了比较。支架移植物刚度显著影响PWV、PP和膨胀性。传统支架移植显示，根据支架长度不同，PWV增加14% - 52% (p < 0.001)， PP增加5% - 32%，移植物中期膨胀率降低82%。相比之下，NF-SGs维持PWV和PP接近基线水平，支架长度影响甚微。根据支架长度的不同，中间移植物的扩张率降低了13% - 20%。NF-SG优越的顺应性和减少的血流动力学扰动归功于其机械优化的织物和骨架设计。这些发现强调了顺应性支架移植的临床潜力，可以显著减轻长期心血管并发症，并在干预后保持主动脉功能。

{"title":"Effect of stent-graft length and compliance on aortic hemodynamics in a bench-top physiological flow circuit","authors":"Ramin Shahbad, Elizabeth Zermeno, Sayed Ahmadreza Razian, Kaspars Maleckis, Majid Jadidi, Anastasia Desyatova","doi":"10.1016/j.jmbbm.2025.107269","DOIUrl":"10.1016/j.jmbbm.2025.107269","url":null,"abstract":"<div><div>The aortic elasticity plays a vital role in buffering pulsatile blood flow, propelling blood to distal organs and the heart, and reducing cardiac workload. Aortic repair with a stent-graft can reduce this elasticity and hinder the aorta's ability to effectively perform its function. Conventional stent-grafts are associated with increased arterial stiffness, elevated pulse wave velocity (PWV), and adverse hemodynamic changes. This is largely driven by stiffness mismatch between the stent-graft and the native aortic wall, which alters mechanical compliance and hemodynamic response. This study evaluates a novel compliant nanofiber stent-graft (NF-SG) developed to closely mimic native aortic mechanics. Using a bench-top physiological flow circuit, we assessed the hemodynamic impacts of stent-graft stiffness and length on arterial parameters, including PWV, pulse pressure (PP), and distensibility in vitro, and compared these effects with conventional stent-grafts. Stent-graft stiffness significantly affected PWV, PP, and distensibility. Conventional stent-grafts showed 14 %–52 % increase in PWV depending on stent-graft length (p < 0.001), 5 %–32 % increase in PP, and 82 % reduction in mid-graft distensibility. In contrast, NF-SGs maintained PWV and PP near baseline levels with marginal effect of the stent-graft length. Distensibility in the mid-graft was reduced by 13 %–20 %, depending on the stent-graft length. The NF-SG's superior compliance and reduced hemodynamic perturbation were attributed to its mechanically optimized fabric and skeleton design. These findings underscore the clinical potential of the compliant stent-grafts to significantly mitigate long-term cardiovascular complications and preserve aortic functionality post-intervention.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107269"},"PeriodicalIF":3.5,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145569484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Protective performance of auxetic TPU pad for helmet: An investigation into design improvements for blunt impact protection 增强型TPU头盔防护垫的防护性能：钝冲击防护设计改进研究。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-10 DOI: 10.1016/j.jmbbm.2025.107254

Zhouyu Shen, Yaoke Wen, Weixiao Nie, Huicheng Wang, Haoran Xu

Traditional helmet foam pads have limited energy absorption for blunt impacts, unable to meet protective needs in complex ballistic scenarios such as fragments and bullets. Auxetic (negative Poisson's ratio) materials have been tested for helmet pads, but existing studies focus mainly on low-velocity impact protection. Thus, optimizing auxetic pad structures for high-velocity impacts is essential.

In this study, lightweight expanded thermoplastic polyurethane (TPU-LW) was used as the base material, with 3D printing to fabricate pad samples. First, TPU-LW's material constitutive model was established via uniaxial tensile tests. Simulations later revealed a key issue: a single auxetic pad caused excessive skull peak stress. To solve this, an innovative “auxetic + foam” composite pad was designed, verified by 9 mm pistol bullet and 1.1 g fragment tests.

The composite pad outperformed single auxetic and foam pads in key head blunt impact indicators. Simulations showed that under high-velocity fragment impact, the helmet's maximum backface deformation (BFD) dropped to 14.50 mm, and skull peak stress was 22.7 % lower than the foam pad. Experiments indicated that under 714 m/s fragment impact, peak head pressure was only 25 kPa - far below the foam pad's 165 kPa.

This study fills the biomechanical data gap of auxetic TPU-LW in ballistic protection. The proposed composite structure provides a theoretical basis and technical solution for upgrading helmet pads from “single-material” to “composite energy-absorbing structure,” applicable to various protective helmet research and development.

传统的头盔泡沫垫对钝冲击的能量吸收有限，无法满足碎片和子弹等复杂弹道场景的保护需求。负泊松比（负泊松比）材料已被用于头盔衬垫的测试，但现有的研究主要集中在低速冲击防护上。因此，优化缓冲垫结构以应对高速撞击是至关重要的。本研究以轻质膨胀型热塑性聚氨酯（TPU-LW）为基材，采用3D打印技术制作垫样。首先，通过单轴拉伸试验建立TPU-LW材料本构模型；后来的模拟揭示了一个关键问题：一个辅助垫会导致颅骨峰值应力过大。为了解决这一问题，设计了一种创新的“消声+泡沫”复合衬垫，并通过9毫米手枪子弹和1.1 g破片试验进行了验证。复合垫块在关键的头部钝性冲击指标上优于单一助剂垫块和泡沫垫块。仿真结果表明，在高速破片冲击下，头盔的最大后面变形量（BFD）降至14.50 mm，颅骨峰值应力比泡沫垫降低22.7%。实验表明，在714 m/s破片冲击下，峰值水头压力仅为25 kPa，远低于泡沫垫的165 kPa。本研究填补了补体TPU-LW在弹道防护方面的生物力学数据空白。本文提出的复合结构为将头盔衬垫从“单一材料”升级为“复合吸能结构”提供了理论基础和技术解决方案，适用于各种防护头盔的研发。

{"title":"Protective performance of auxetic TPU pad for helmet: An investigation into design improvements for blunt impact protection","authors":"Zhouyu Shen, Yaoke Wen, Weixiao Nie, Huicheng Wang, Haoran Xu","doi":"10.1016/j.jmbbm.2025.107254","DOIUrl":"10.1016/j.jmbbm.2025.107254","url":null,"abstract":"<div><div>Traditional helmet foam pads have limited energy absorption for blunt impacts, unable to meet protective needs in complex ballistic scenarios such as fragments and bullets. Auxetic (negative Poisson's ratio) materials have been tested for helmet pads, but existing studies focus mainly on low-velocity impact protection. Thus, optimizing auxetic pad structures for high-velocity impacts is essential.</div><div>In this study, lightweight expanded thermoplastic polyurethane (TPU-LW) was used as the base material, with 3D printing to fabricate pad samples. First, TPU-LW's material constitutive model was established via uniaxial tensile tests. Simulations later revealed a key issue: a single auxetic pad caused excessive skull peak stress. To solve this, an innovative “auxetic + foam” composite pad was designed, verified by 9 mm pistol bullet and 1.1 g fragment tests.</div><div>The composite pad outperformed single auxetic and foam pads in key head blunt impact indicators. Simulations showed that under high-velocity fragment impact, the helmet's maximum backface deformation (BFD) dropped to 14.50 mm, and skull peak stress was 22.7 % lower than the foam pad. Experiments indicated that under 714 m/s fragment impact, peak head pressure was only 25 kPa - far below the foam pad's 165 kPa.</div><div>This study fills the biomechanical data gap of auxetic TPU-LW in ballistic protection. The proposed composite structure provides a theoretical basis and technical solution for upgrading helmet pads from “single-material” to “composite energy-absorbing structure,” applicable to various protective helmet research and development.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107254"},"PeriodicalIF":3.5,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Systematic biomechanical evaluation of different dental implant materials at various bone stock conditions using a statistical and subject-specific computer-based workflow 系统的生物力学评估不同的牙种植材料在不同的骨储备条件下使用统计和主题特定的计算机为基础的工作流程。

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials

Pub Date : 2025-11-07 DOI: 10.1016/j.jmbbm.2025.107255

Jan-Oliver Sass , Iman Soodmand , Ann-Kristin Becker , Christopher Jabs , Michael Dau , Rainer Bader , Maeruan Kebbach

This computational study aimed to evaluate the bone-implant interaction of dental implants made from materials with varying Young's moduli under various conditions of bone quality. A subject-specific numerical workflow was developed by integrating boundary conditions obtained from a musculoskeletal multibody simulation (MMBS) into a finite element (FE) analysis of the mandible bone. Implants made from commercially pure titanium (cp-Ti), zirconia ceramic (ZrO₂), low-stiffness β-titanium alloy (β-Ti), and poly-ether-ether-ketone (PEEK) were evaluated during a clenching scenario. A systematic analysis was performed using statistical modeling to examine ten variations in bone quality, including cortical thickness and homogeneous bone stiffness. Additionally, two CT-based subject-specific comparisons were carried out using mandibles with distinctly different bone qualities. Implants made from materials with lower stiffness resulted in increased peri-implant strain and stress levels. In the statistical analysis, these effects were not significant when accounting for inter-individual variability of the bone qualities (p > 0.05). Cortical bone stiffness strongly correlated with peri-implant bone stress (r = 0.96 ± 0.01), while trabecular bone stiffness correlated with maximum (r = 0.71 ± 0.01) and minimum (r = −0.83 ± 0.02) principal strain in the bone. In the subject-specific analysis, stress and strain in the peri-implant bone increased for the low-quality bone and were significant for a PEEK-based implant (p < 0.001). Within the restrictions of the simplified numerical models and limited generalizability of the present findings, materials with lower stiffness may reduce peri-implant stress shielding but simultaneously increase stress at the bone-implant interface. However, their overall effect was not statistically significant when inter-individual variation in bone quality were considered.

本计算研究旨在评估由不同杨氏模量材料制成的牙种植体在不同骨质量条件下的骨-种植体相互作用。通过将肌肉骨骼多体模拟（MMBS）得到的边界条件整合到下颌骨的有限元分析中，开发了一个特定主题的数值工作流程。由商业纯钛（cp-Ti）、氧化锆陶瓷（ZrO2）、低刚度β-钛合金（β-Ti）和聚醚-醚酮（PEEK）制成的种植体在咬合场景下进行评估。使用统计模型进行系统分析，以检查骨质量的十种变化，包括皮质厚度和均匀骨刚度。此外，使用具有明显不同骨质量的下颌骨进行了两次基于ct的受试者特异性比较。由硬度较低的材料制成的种植体会增加种植体周围的应变和应力水平。在统计分析中，当考虑到骨质量的个体间差异时，这些影响并不显著（p < 0.05）。骨皮质刚度与种植体周围骨应力呈显著相关（r = 0.96±0.01），骨小梁刚度与骨最大主应变（r = 0.71±0.01）和最小主应变（r = -0.83±0.02）呈显著相关。在受试者特异性分析中，低质量骨的种植体周围骨的应力和应变增加，对于基于peek的种植体来说是显著的(p

{"title":"Systematic biomechanical evaluation of different dental implant materials at various bone stock conditions using a statistical and subject-specific computer-based workflow","authors":"Jan-Oliver Sass , Iman Soodmand , Ann-Kristin Becker , Christopher Jabs , Michael Dau , Rainer Bader , Maeruan Kebbach","doi":"10.1016/j.jmbbm.2025.107255","DOIUrl":"10.1016/j.jmbbm.2025.107255","url":null,"abstract":"<div><div>This computational study aimed to evaluate the bone-implant interaction of dental implants made from materials with varying Young's moduli under various conditions of bone quality. A subject-specific numerical workflow was developed by integrating boundary conditions obtained from a musculoskeletal multibody simulation (MMBS) into a finite element (FE) analysis of the mandible bone. Implants made from commercially pure titanium (cp-Ti), zirconia ceramic (ZrO<sub>2</sub>), low-stiffness β-titanium alloy (β-Ti), and poly-ether-ether-ketone (PEEK) were evaluated during a clenching scenario. A systematic analysis was performed using statistical modeling to examine ten variations in bone quality, including cortical thickness and homogeneous bone stiffness. Additionally, two CT-based subject-specific comparisons were carried out using mandibles with distinctly different bone qualities. Implants made from materials with lower stiffness resulted in increased peri-implant strain and stress levels. In the statistical analysis, these effects were not significant when accounting for inter-individual variability of the bone qualities (p > 0.05). Cortical bone stiffness strongly correlated with peri-implant bone stress (r = 0.96 ± 0.01), while trabecular bone stiffness correlated with maximum (r = 0.71 ± 0.01) and minimum (r = −0.83 ± 0.02) principal strain in the bone. In the subject-specific analysis, stress and strain in the peri-implant bone increased for the low-quality bone and were significant for a PEEK-based implant (p < 0.001). Within the restrictions of the simplified numerical models and limited generalizability of the present findings, materials with lower stiffness may reduce peri-implant stress shielding but simultaneously increase stress at the bone-implant interface. However, their overall effect was not statistically significant when inter-individual variation in bone quality were considered.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107255"},"PeriodicalIF":3.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145508569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0