Pub Date : 2024-09-30DOI: 10.1177/10567895241277657
Hui Wang, Zhichao Xu, Hongyuan Huai, Yunteng Yin, Jiacong Zeng, Zhihao Du, Hang Zhou
In order to study the effects of crack inclination angle and loading rate on rock mechanical properties, creep characteristics, and failure characteristics. Taking homogeneous red sandstone with different fracture angles as the research object, uniaxial compression tests and uniaxial compression creep tests were conducted at different loading rates. The results showed that under the same fracture angle, the loading rate was positively correlated with the peak strength, elastic modulus, instantaneous strain, creep strain, and steady-state creep rate of the sample, while negatively correlated with the peak strain. At the same loading rate, the mechanical properties and creep properties of the sample were controlled by the crack inclination angle α. With the increase of α, the peak strength, peak strain, instantaneous strain, creep strain and steady-state creep rate decreased first and then increased, and the elastic modulus increased. On the basis of rock creep testing, it is also important to establish a creep model that conforms to the actual test situation for studying rock creep characteristics. However, many models currently used cannot accurately describe the three stages of rock creep, especially the accelerated creep stage. Therefore, based on Burgers elements, this paper introduces plastic damage bodies based on damage rates and software components based on fractional calculus, A new creep model was obtained and its rationality was verified through experimental results. The results showed that the fit between the model and experimental data was above 0.97, indicating that the model can better describe the three stages of rock creep, especially reflecting the non-linear characteristics of the accelerated creep stage.
{"title":"Experimental study on the mechanical properties of red sandstone with fractures under different loading rates","authors":"Hui Wang, Zhichao Xu, Hongyuan Huai, Yunteng Yin, Jiacong Zeng, Zhihao Du, Hang Zhou","doi":"10.1177/10567895241277657","DOIUrl":"https://doi.org/10.1177/10567895241277657","url":null,"abstract":"In order to study the effects of crack inclination angle and loading rate on rock mechanical properties, creep characteristics, and failure characteristics. Taking homogeneous red sandstone with different fracture angles as the research object, uniaxial compression tests and uniaxial compression creep tests were conducted at different loading rates. The results showed that under the same fracture angle, the loading rate was positively correlated with the peak strength, elastic modulus, instantaneous strain, creep strain, and steady-state creep rate of the sample, while negatively correlated with the peak strain. At the same loading rate, the mechanical properties and creep properties of the sample were controlled by the crack inclination angle α. With the increase of α, the peak strength, peak strain, instantaneous strain, creep strain and steady-state creep rate decreased first and then increased, and the elastic modulus increased. On the basis of rock creep testing, it is also important to establish a creep model that conforms to the actual test situation for studying rock creep characteristics. However, many models currently used cannot accurately describe the three stages of rock creep, especially the accelerated creep stage. Therefore, based on Burgers elements, this paper introduces plastic damage bodies based on damage rates and software components based on fractional calculus, A new creep model was obtained and its rationality was verified through experimental results. The results showed that the fit between the model and experimental data was above 0.97, indicating that the model can better describe the three stages of rock creep, especially reflecting the non-linear characteristics of the accelerated creep stage.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142360550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-27DOI: 10.1177/10567895241282229
Abel Cherouat, Thierry Barriere, Hong Wang
In this study, a comprehensive investigation was conducted to explore the material extrusion process of NiTi shape-memory alloy-based bio-composite polymeric matrix. Polylactic acid PLA+ Stearic Acid polymeric matrix are performed in order to develop an environmentally friendly process for manufacturing feedstocks with [Formula: see text] nickel-titanium powders for employed in the 3D printing process. The additive manufacturing process based on the extrusion of materials will be studied at all stages (feedstock manufacturing with nickel-titanium powders, 3D printing of bio-composite green part, thermal debinding, and densification by solid-state diffusion) using experimental approaches, analytical approaches to predict printability index and thermo-physical analyses for the formulation of NiTi and biocomposite binders. Printing parameters were optimized by analysing the microstructure, rheological, mechanical properties of feedstock and 3D printed parts. Static mechanical tests will be performed in association with numerical modelling to study the evolution of damage for fully densified SMA specimens in order to describe the ductile failure of 3D printed specimens. Micromechanical phenomenological constitutive models are used in Finite Element software and which can account for the damage localization, initiation and damage growth based on continuum damage mechanics. The results of this study can be used to optimize the extrusion process parameters for different materials and can be helpful for researchers and industrialists to further explore and develop sustainable and eco-friendly materials.
本研究对基于镍钛形状记忆合金的生物复合聚合物基体的材料挤压工艺进行了全面调查。聚乳酸 PLA+ 硬脂酸聚合基体，以开发出一种环保型工艺，用于制造含有[配方：见正文]镍钛粉末的原料，并将其应用于三维打印工艺中。将利用实验方法、预测可打印性指数的分析方法以及镍钛和生物复合材料粘合剂配方的热物理分析方法，研究基于材料挤压的添加制造工艺的各个阶段（镍钛粉末原料制造、生物复合材料绿色部件的三维打印、热脱粘和固态扩散致密化）。通过分析原料和三维打印部件的微观结构、流变学和机械性能，对打印参数进行了优化。静态机械测试将与数值建模相结合，研究全致密 SMA 试样的损伤演变，以描述 3D 打印试样的韧性破坏。有限元软件中使用了微观机械现象学构成模型，该模型可在连续损伤力学的基础上解释损伤定位、起始和损伤增长。本研究的结果可用于优化不同材料的挤压工艺参数，并有助于研究人员和工业家进一步探索和开发可持续的环保材料。
{"title":"Experimental analysis of extrusion-based additive manufacturing process of bio-composite NiTi alloy","authors":"Abel Cherouat, Thierry Barriere, Hong Wang","doi":"10.1177/10567895241282229","DOIUrl":"https://doi.org/10.1177/10567895241282229","url":null,"abstract":"In this study, a comprehensive investigation was conducted to explore the material extrusion process of NiTi shape-memory alloy-based bio-composite polymeric matrix. Polylactic acid PLA+ Stearic Acid polymeric matrix are performed in order to develop an environmentally friendly process for manufacturing feedstocks with [Formula: see text] nickel-titanium powders for employed in the 3D printing process. The additive manufacturing process based on the extrusion of materials will be studied at all stages (feedstock manufacturing with nickel-titanium powders, 3D printing of bio-composite green part, thermal debinding, and densification by solid-state diffusion) using experimental approaches, analytical approaches to predict printability index and thermo-physical analyses for the formulation of NiTi and biocomposite binders. Printing parameters were optimized by analysing the microstructure, rheological, mechanical properties of feedstock and 3D printed parts. Static mechanical tests will be performed in association with numerical modelling to study the evolution of damage for fully densified SMA specimens in order to describe the ductile failure of 3D printed specimens. Micromechanical phenomenological constitutive models are used in Finite Element software and which can account for the damage localization, initiation and damage growth based on continuum damage mechanics. The results of this study can be used to optimize the extrusion process parameters for different materials and can be helpful for researchers and industrialists to further explore and develop sustainable and eco-friendly materials.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142328701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1177/10567895241279842
A Goumghar, K Azouaoui, M Assarar, W Zouari, S Mouhoubi, R Ayad, A El Mahi
The aim of this study is to investigate the fatigue behaviour of hybrid flax-glass/epoxy composites under repeated impact loading subsequent to water ageing. Different plates of these composite materials were fabricated using the vacuum infusion technique. Five stacking sequences were considered: [F8], [G/F3]S, [G2/F2]S, [G3/F]S, and [G8], where F and G stand for flax/epoxy and glass/epoxy plies, respectively. Water ageing was conducted by immersing the composite specimens in tap water at room temperature for various durations, and until saturation was reached. Fatigue impact tests were carried out using three impact energies: 3, 4, and 5 J. An advanced high-resolution camera was used to monitor the evolution of damage mechanisms occurring on the non-impacted surfaces, while a laser thermometer was considered to track the temperature variations within each composite specimen. The obtained results show that flax-glass hybridization reduces the mass of absorbed water in flax/epoxy composite by up to 70%. Furthermore, there is a more pronounced decrease in longitudinal modulus and maximum stress in aged composites, with reductions of up to 70% compared to unaged ones. Additionally, visible damage occurs even at low energy levels, manifesting from the initial impacts in both aged and unaged composite laminates. Moreover, a correlation between the number of impacts to failure and the cumulative energy is revealed. Ultimately, water aging reduces the strength of the studied composite laminates and their resistance to impact fatigue. Furthermore, the hybrid laminates with high proportion of flax layers are particularly susceptible to water ageing effects.
本研究的目的是调查亚麻-玻璃-环氧混合复合材料在水老化后反复冲击加载下的疲劳行为。采用真空灌注技术制造了这些复合材料的不同板材。考虑了五种堆叠序列：[F8]、[G/F3]S、[G2/F2]S、[G3/F]S 和 [G8]，其中 F 和 G 分别代表亚麻/环氧层和玻璃/环氧层。水老化是将复合材料试样浸泡在室温下的自来水中，浸泡时间长短不一，直至达到饱和状态。疲劳冲击试验采用三种冲击能量进行：先进的高分辨率照相机用于监控非撞击表面的损伤机制演变，而激光温度计则用于跟踪每个复合材料试样内部的温度变化。研究结果表明，亚麻-玻璃杂化使亚麻/环氧复合材料的吸水率降低了 70%。此外，在老化的复合材料中，纵向模量和最大应力的下降更为明显，与未老化的复合材料相比，降幅高达 70%。此外，即使在低能量水平下，老化和未老化的复合材料层压板也会从最初的冲击开始出现明显的损坏。此外，还发现了冲击到破坏的次数与累积能量之间的相关性。最终，水老化降低了所研究的复合材料层压板的强度及其抗冲击疲劳的能力。此外，亚麻层比例较高的混合层压板尤其容易受到水老化效应的影响。
{"title":"Damage investigation of hybrid flax-glass/epoxy composites subjected to impact fatigue under water ageing","authors":"A Goumghar, K Azouaoui, M Assarar, W Zouari, S Mouhoubi, R Ayad, A El Mahi","doi":"10.1177/10567895241279842","DOIUrl":"https://doi.org/10.1177/10567895241279842","url":null,"abstract":"The aim of this study is to investigate the fatigue behaviour of hybrid flax-glass/epoxy composites under repeated impact loading subsequent to water ageing. Different plates of these composite materials were fabricated using the vacuum infusion technique. Five stacking sequences were considered: [F<jats:sub>8</jats:sub>], [G/F<jats:sub>3</jats:sub>]<jats:sub>S</jats:sub>, [G<jats:sub>2</jats:sub>/F<jats:sub>2</jats:sub>]<jats:sub>S</jats:sub>, [G<jats:sub>3</jats:sub>/F]<jats:sub>S</jats:sub>, and [G<jats:sub>8</jats:sub>], where F and G stand for flax/epoxy and glass/epoxy plies, respectively. Water ageing was conducted by immersing the composite specimens in tap water at room temperature for various durations, and until saturation was reached. Fatigue impact tests were carried out using three impact energies: 3, 4, and 5 J. An advanced high-resolution camera was used to monitor the evolution of damage mechanisms occurring on the non-impacted surfaces, while a laser thermometer was considered to track the temperature variations within each composite specimen. The obtained results show that flax-glass hybridization reduces the mass of absorbed water in flax/epoxy composite by up to 70%. Furthermore, there is a more pronounced decrease in longitudinal modulus and maximum stress in aged composites, with reductions of up to 70% compared to unaged ones. Additionally, visible damage occurs even at low energy levels, manifesting from the initial impacts in both aged and unaged composite laminates. Moreover, a correlation between the number of impacts to failure and the cumulative energy is revealed. Ultimately, water aging reduces the strength of the studied composite laminates and their resistance to impact fatigue. Furthermore, the hybrid laminates with high proportion of flax layers are particularly susceptible to water ageing effects.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142317537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1177/10567895241280788
Lorenzo Pagliari, Franco Concli
Most of real-world structural components that undergo cyclic loading feature multiaxial fatigue. When the cyclic loading involves also significant plastic deformation, multiaxial low-cycle fatigue takes place. Applications where multiaxial low-cycle fatigue can be observed very often involve metal components. To predict their lives multiple criteria and models have been proposed, but their development has not followed a regular path. Multiple reviews are available in literature. However, many of them are outdated, they often employ different classification methods to categorize available criteria, many focus on specific families of criteria, and others do not include sufficient theoretical background. Moreover, none of the available reviews is based on a systematic literature search method. As a result, approaching the topic can result arduous and chaotic, especially for first timers. This work aims at providing a clear, comprehensive, and definitive review of available criteria for multiaxial low-cycle fatigue. First, the basic theoretical background is explained. Secondly, a systematic approach is described and employed to identify all major currently available criteria. Then, they are classified and commentary about different classification styles that can be found in literature is added. Eventually they are described, together with their latest proposed variations. In this way this review can be employed as a guiding reference, especially for engineers approaching the topic for the first time.
{"title":"A review of multiaxial low-cycle fatigue criteria for life prediction of metals","authors":"Lorenzo Pagliari, Franco Concli","doi":"10.1177/10567895241280788","DOIUrl":"https://doi.org/10.1177/10567895241280788","url":null,"abstract":"Most of real-world structural components that undergo cyclic loading feature multiaxial fatigue. When the cyclic loading involves also significant plastic deformation, multiaxial low-cycle fatigue takes place. Applications where multiaxial low-cycle fatigue can be observed very often involve metal components. To predict their lives multiple criteria and models have been proposed, but their development has not followed a regular path. Multiple reviews are available in literature. However, many of them are outdated, they often employ different classification methods to categorize available criteria, many focus on specific families of criteria, and others do not include sufficient theoretical background. Moreover, none of the available reviews is based on a systematic literature search method. As a result, approaching the topic can result arduous and chaotic, especially for first timers. This work aims at providing a clear, comprehensive, and definitive review of available criteria for multiaxial low-cycle fatigue. First, the basic theoretical background is explained. Secondly, a systematic approach is described and employed to identify all major currently available criteria. Then, they are classified and commentary about different classification styles that can be found in literature is added. Eventually they are described, together with their latest proposed variations. In this way this review can be employed as a guiding reference, especially for engineers approaching the topic for the first time.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142317545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1177/10567895241279845
Xikun Wu, Geoffrey Ginoux, Joseph Paux, Samir Allaoui
Additive manufacturing (AM) of continuous yarn-reinforced biobased composites presents multi-functional properties and low environmental impact of this technology. Few studies focused on the mechanical damage mechanisms of continuous biobased composites obtained by AM processes, while it is a topic of high interest for the mastery of mechanical behaviors and optimization of the materials for high requirement applications. This study aims to assess the damage and fracture modes of continuous flax yarn-reinforced PLA manufactured by AM, with different yarn orientations. The additively manufactured biobased composites were characterized by tensile test, 3D microscopy and micro-tomography to link the process-structure-properties relationships regarding the damage and fracture modes. The results showed that the 0° manufactured composite had a significant enhancement of tensile properties compared to other configurations. The damage mechanism presented fiber rupture with polymer transverse cracks at 0°, while the 45° and 90°-oriented composites showed premature fiber/matrix interface debonding. This study aims to find the relationship between damage mechanisms, deposition strategy, and anisotropy of the additively manufactured long vegetal fibers-reinforced biobased composite materials. The results bring a new understanding of the anisotropy and defects in printed composite materials regarding their mechanical behaviors during damage.
连续纱线增强生物基复合材料的快速成型（AM）技术具有多功能特性和低环境影响的特点。很少有研究关注通过 AM 工艺获得的连续生物基复合材料的机械损伤机理，而这对于掌握高要求应用领域的机械行为和优化材料是一个非常有意义的课题。本研究旨在评估 AM 制造的不同纱线取向的连续亚麻纱线增强聚乳酸的损伤和断裂模式。通过拉伸试验、三维显微镜和显微层析成像技术对添加剂制造的生物基复合材料进行表征，以联系有关损伤和断裂模式的工艺-结构-性能关系。结果表明，与其他结构相比，0°制造的复合材料的拉伸性能显著提高。损伤机制表现为 0° 方向的纤维断裂和聚合物横向裂纹，而 45° 和 90° 方向的复合材料则表现为过早的纤维/基质界面脱粘。本研究旨在探究加成制造的长植物纤维增强生物基复合材料的损伤机制、沉积策略和各向异性之间的关系。研究结果使人们对印刷复合材料的各向异性和缺陷在损坏过程中的力学行为有了新的认识。
{"title":"Damage and fracture studies of continuous flax fiber-reinforced composites 3D printed by in-nozzle impregnation additive manufacturing","authors":"Xikun Wu, Geoffrey Ginoux, Joseph Paux, Samir Allaoui","doi":"10.1177/10567895241279845","DOIUrl":"https://doi.org/10.1177/10567895241279845","url":null,"abstract":"Additive manufacturing (AM) of continuous yarn-reinforced biobased composites presents multi-functional properties and low environmental impact of this technology. Few studies focused on the mechanical damage mechanisms of continuous biobased composites obtained by AM processes, while it is a topic of high interest for the mastery of mechanical behaviors and optimization of the materials for high requirement applications. This study aims to assess the damage and fracture modes of continuous flax yarn-reinforced PLA manufactured by AM, with different yarn orientations. The additively manufactured biobased composites were characterized by tensile test, 3D microscopy and micro-tomography to link the process-structure-properties relationships regarding the damage and fracture modes. The results showed that the 0° manufactured composite had a significant enhancement of tensile properties compared to other configurations. The damage mechanism presented fiber rupture with polymer transverse cracks at 0°, while the 45° and 90°-oriented composites showed premature fiber/matrix interface debonding. This study aims to find the relationship between damage mechanisms, deposition strategy, and anisotropy of the additively manufactured long vegetal fibers-reinforced biobased composite materials. The results bring a new understanding of the anisotropy and defects in printed composite materials regarding their mechanical behaviors during damage.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142245630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-14DOI: 10.1177/10567895241277681
Qiuxin Gu, Qiang Zhang, Wanli Dai, Xiaowei Quan, Sizhe Ye, Tao Li
The shear constitutive model of rock joints is of great significance to the stability analysis in rock engineering, and it is closely related to the normal stress ([Formula: see text]) and joint roughness coefficient ( JRC). However, the existing investigations seldom consider the influences of [Formula: see text] and JRC simultaneously. Therefore, a novel damage constitutive model considering the [Formula: see text] and JRC is developed in this work. In the presented model, it is assumed that the rock materials are composed of damaged and undamaged microunits, and the damage evolution law of the microunits conforms to the Weibull distribution in the shear process. Based on the proposed assumption, the constitutive relationship between shear stress and shear displacement is deduced. The evolutions of the mechanical parameters and damage variable versus [Formula: see text] and JRC are analyzed in detail. The proposed damage model that involves [Formula: see text] and JRC is verified by comparing theoretical values with the laboratory results. The results show that the damage constitutive model is in good agreement with the test results. Additionally, the influences of [Formula: see text] and JRC on the shear stress-displacement curves are studied. This work can provide a valuable theoretical method for analyzing the shear mechanical characteristics and damage evolution laws of rock joints.
{"title":"A novel statistical damage constitutive model of rock joints considering normal stress and joint roughness","authors":"Qiuxin Gu, Qiang Zhang, Wanli Dai, Xiaowei Quan, Sizhe Ye, Tao Li","doi":"10.1177/10567895241277681","DOIUrl":"https://doi.org/10.1177/10567895241277681","url":null,"abstract":"The shear constitutive model of rock joints is of great significance to the stability analysis in rock engineering, and it is closely related to the normal stress ([Formula: see text]) and joint roughness coefficient ( JRC). However, the existing investigations seldom consider the influences of [Formula: see text] and JRC simultaneously. Therefore, a novel damage constitutive model considering the [Formula: see text] and JRC is developed in this work. In the presented model, it is assumed that the rock materials are composed of damaged and undamaged microunits, and the damage evolution law of the microunits conforms to the Weibull distribution in the shear process. Based on the proposed assumption, the constitutive relationship between shear stress and shear displacement is deduced. The evolutions of the mechanical parameters and damage variable versus [Formula: see text] and JRC are analyzed in detail. The proposed damage model that involves [Formula: see text] and JRC is verified by comparing theoretical values with the laboratory results. The results show that the damage constitutive model is in good agreement with the test results. Additionally, the influences of [Formula: see text] and JRC on the shear stress-displacement curves are studied. This work can provide a valuable theoretical method for analyzing the shear mechanical characteristics and damage evolution laws of rock joints.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-14DOI: 10.1177/10567895241277951
Mykola Bobyr, Vadim Silberchmidt, Viktor Koval
A low-cycle fatigue (LCF) analysis is one of the main design stages for highly loaded structural elements used in various applications. For this analysis, it is necessary to determine the values of local stresses and deformations, taking into account both elastic and plastic regions in the zones of stress concentration. This study presents and assesses the engineering methods used for prediction of low-cycle fatigue in structural elements. For zones of stress (strain) concentration, the Neuber-Makhutov method for LCF, taking into account the type of material stress-strain diagrams, is employed. The concept of distributed damage, based on the main ideas of the continuum damage mechanics of Kachanov-Rabotnov, was used. An approach employing the damage parameter for assessment of damage accumulation in LCF in highly loaded areas of structural elements is presented.
{"title":"Effort of damage parameter in assessment of low cycle fatigue","authors":"Mykola Bobyr, Vadim Silberchmidt, Viktor Koval","doi":"10.1177/10567895241277951","DOIUrl":"https://doi.org/10.1177/10567895241277951","url":null,"abstract":"A low-cycle fatigue (LCF) analysis is one of the main design stages for highly loaded structural elements used in various applications. For this analysis, it is necessary to determine the values of local stresses and deformations, taking into account both elastic and plastic regions in the zones of stress concentration. This study presents and assesses the engineering methods used for prediction of low-cycle fatigue in structural elements. For zones of stress (strain) concentration, the Neuber-Makhutov method for LCF, taking into account the type of material stress-strain diagrams, is employed. The concept of distributed damage, based on the main ideas of the continuum damage mechanics of Kachanov-Rabotnov, was used. An approach employing the damage parameter for assessment of damage accumulation in LCF in highly loaded areas of structural elements is presented.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aim of this work was to evaluate the tensile properties and the damage mechanisms of hemp and glass-reinforced composites when they were subjected to hydrothermal fatigue. Each wet/dry cycle consisted in immersing samples in water at 60°C during 12 days and drying them in an oven at 40°C during 2 days. Three different matrices (Epolam, Greenpoxy and Elium) were studied with two reinforcement orientations (±45° and 0°/90°). Gravimetric measurements were performed during 30 wet/dry cycles to determine the evolution of the parameters of the Fick diffusion model. Repeated progressive tensile loading tests instrumented with an acoustic emission setup were also carried out. Damage was investigated by means of SEM and micro-CT. Results showed that hydrothermal fatigue affects significantly the tensile properties of all the composites studied. Hemp/Greenpoxy appears to better resist to hydrothermal fatigue while the hemp/Elium behavior is more impacted. Moreover, contrary to what might be expected, glass/Epolam samples are not the least sensitive to hydrothermal fatigue.
{"title":"Influence of hydrothermal fatigue on mechanical properties and damage mechanisms of hemp-reinforced biocomposites and comparison with glass-reinforced composites","authors":"Quentin Drouhet, Fabienne Touchard, Laurence Chocinski-Arnault","doi":"10.1177/10567895241280375","DOIUrl":"https://doi.org/10.1177/10567895241280375","url":null,"abstract":"The aim of this work was to evaluate the tensile properties and the damage mechanisms of hemp and glass-reinforced composites when they were subjected to hydrothermal fatigue. Each wet/dry cycle consisted in immersing samples in water at 60°C during 12 days and drying them in an oven at 40°C during 2 days. Three different matrices (Epolam, Greenpoxy and Elium) were studied with two reinforcement orientations (±45° and 0°/90°). Gravimetric measurements were performed during 30 wet/dry cycles to determine the evolution of the parameters of the Fick diffusion model. Repeated progressive tensile loading tests instrumented with an acoustic emission setup were also carried out. Damage was investigated by means of SEM and micro-CT. Results showed that hydrothermal fatigue affects significantly the tensile properties of all the composites studied. Hemp/Greenpoxy appears to better resist to hydrothermal fatigue while the hemp/Elium behavior is more impacted. Moreover, contrary to what might be expected, glass/Epolam samples are not the least sensitive to hydrothermal fatigue.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-14DOI: 10.1177/10567895241282416
Zoran B Perović, Dragoslav M Šumarac, Stanko B Ćorić, Petar M Knežević, Maosen Cao, Ismail Nurković
A uniaxial material model for fatigue damage accumulation, established on the connection of unit elements, is presented in this paper. Although these units are regarded as micro-elements in the proposed model, they are based on a hysteretic operator that enables calculating hysteretic energy loss as an analytical expression. Further, this unit element represents a mechanical model with elastoplastic damage behavior in function of strain. The second level of modeling is defined by the connection of these units (micro-elements) with different values of total energy dissipated at failure. By changing the distribution of dissipated energy limit, various fatigue damage evolution laws are developed. Calculation of total and hysteretic energy loss in one loading cycle is also affected by fatigue damage as the varying number of unit elements are been eliminated when their maximum dissipation energy is reached. Material parameters for the model were defined based on the experimental monotonic and cyclic stress-strain tests, still, detailed comparison was not performed as the main advantage and aim of the paper was the development of the method for assessment of damage evolution in fatigue analysis. On the other hand, the number of cycles to failure ( Nf) and total heat dissipation are compared in both qualitative and quantitative aspects with experimental results. Finally, based on the proposed model, mean strain and load sequence effect diagrams were constructed. It is shown that the proposed model can provide a reliable estimation of fatigue life in the low-cycle regime of loading. The maximum error for the calculated Nf was 3% for constant strain loading for experiments with strain amplitude less than 5%. In load sequence fatigue life estimation, the proposed model demonstrated good accuracy, with a maximum error of 34%. Further, obtained results were achieved with different types of damage evolution that could be defined for the same material and fatigue life.
{"title":"Energy based damage model for low-cycle fatigue of ductile materials","authors":"Zoran B Perović, Dragoslav M Šumarac, Stanko B Ćorić, Petar M Knežević, Maosen Cao, Ismail Nurković","doi":"10.1177/10567895241282416","DOIUrl":"https://doi.org/10.1177/10567895241282416","url":null,"abstract":"A uniaxial material model for fatigue damage accumulation, established on the connection of unit elements, is presented in this paper. Although these units are regarded as micro-elements in the proposed model, they are based on a hysteretic operator that enables calculating hysteretic energy loss as an analytical expression. Further, this unit element represents a mechanical model with elastoplastic damage behavior in function of strain. The second level of modeling is defined by the connection of these units (micro-elements) with different values of total energy dissipated at failure. By changing the distribution of dissipated energy limit, various fatigue damage evolution laws are developed. Calculation of total and hysteretic energy loss in one loading cycle is also affected by fatigue damage as the varying number of unit elements are been eliminated when their maximum dissipation energy is reached. Material parameters for the model were defined based on the experimental monotonic and cyclic stress-strain tests, still, detailed comparison was not performed as the main advantage and aim of the paper was the development of the method for assessment of damage evolution in fatigue analysis. On the other hand, the number of cycles to failure ( N<jats:sub>f</jats:sub>) and total heat dissipation are compared in both qualitative and quantitative aspects with experimental results. Finally, based on the proposed model, mean strain and load sequence effect diagrams were constructed. It is shown that the proposed model can provide a reliable estimation of fatigue life in the low-cycle regime of loading. The maximum error for the calculated N<jats:sub>f</jats:sub> was 3% for constant strain loading for experiments with strain amplitude less than 5%. In load sequence fatigue life estimation, the proposed model demonstrated good accuracy, with a maximum error of 34%. Further, obtained results were achieved with different types of damage evolution that could be defined for the same material and fatigue life.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on the damage characteristics of multistage shear creep in weak intercalated layers (carbonaceous mud shale) of slopes under the influence of dynamic disturbance, the effective bearing area method was used. A new coupled damage equation (dynamic disturbance damage, shear creep damage, and initial damage) was established through further derivation, and its applicability was demonstrated. The calculation method for the relevant coupled damage degrees was also provided. Furthermore, by targeting the three coupled damage factors and extending the Kachanov damage law, a time-dependent damage evolution equation for weak intercalated layers under the influence of the three coupled damage effects was established. The influence of different dynamic disturbance intensities on the evolution of multistage shear creep damage in weak intercalated layers of slopes under the influence of coupled damage effects was analysed. The results show that the damage to the rock mass caused by dynamic disturbance mainly occurs in the low-frequency stage (40–80 Hz). The instantaneous damage caused by dynamic disturbance to the shear plane of weak intercalated layers is not only affected by the intensity of the dynamic disturbance but also limited by the magnitude of the shear creep load. The influence of the dynamic disturbance intensity on the entire process of multistage shear creep damage of weak intercalated layers was analysed. With increasing of dynamic disturbance intensity, the cumulative coupled damage at the end of shear creep at all levels gradually exhibits linear evolution. The time-dependent coupling damage evolution process of weak intercalated layers was quantitatively characterized.
{"title":"Analysis of dynamic disturbance and multistage shear creep damage evolution law of the weak intercalated layers in slope under the influence of coupled damage effect","authors":"Zeqi Wang, Bin Hu, Jing Li, Kuikui Chen, Zhuoxi Zhong, Xiangyu Zhang","doi":"10.1177/10567895241277226","DOIUrl":"https://doi.org/10.1177/10567895241277226","url":null,"abstract":"Based on the damage characteristics of multistage shear creep in weak intercalated layers (carbonaceous mud shale) of slopes under the influence of dynamic disturbance, the effective bearing area method was used. A new coupled damage equation (dynamic disturbance damage, shear creep damage, and initial damage) was established through further derivation, and its applicability was demonstrated. The calculation method for the relevant coupled damage degrees was also provided. Furthermore, by targeting the three coupled damage factors and extending the Kachanov damage law, a time-dependent damage evolution equation for weak intercalated layers under the influence of the three coupled damage effects was established. The influence of different dynamic disturbance intensities on the evolution of multistage shear creep damage in weak intercalated layers of slopes under the influence of coupled damage effects was analysed. The results show that the damage to the rock mass caused by dynamic disturbance mainly occurs in the low-frequency stage (40–80 Hz). The instantaneous damage caused by dynamic disturbance to the shear plane of weak intercalated layers is not only affected by the intensity of the dynamic disturbance but also limited by the magnitude of the shear creep load. The influence of the dynamic disturbance intensity on the entire process of multistage shear creep damage of weak intercalated layers was analysed. With increasing of dynamic disturbance intensity, the cumulative coupled damage at the end of shear creep at all levels gradually exhibits linear evolution. The time-dependent coupling damage evolution process of weak intercalated layers was quantitatively characterized.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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