Pub Date : 2024-08-01DOI: 10.1177/00219983241271004
Mohamed Slamani, Hamza Chafai, Jean-François Chatelain
Flax/epoxy composites are recognized as an eco-friendly alternative to synthetic fibers in engineering. Understanding how fiber orientation affects cutting forces and surface characteristics is essential for machining these materials. This study investigates the relationship between fiber orientation and cutting forces (feed, normal, passive) as well as surface roughness in flax/epoxy composites. Results show that fiber orientation significantly impacts cutting forces. Cutting parallel to fibers (0° and 90° orientations) generally requires less force, with 0° needing higher normal force. At 0° orientation, feed force is 46.47 N, normal force is 58.86 N, and passive force is 54.44 N. At 90° orientation, feed force is 56.66 N, normal force is 44.68 N, and passive force is 50.95 N. Oblique orientations (45° and −45°) require higher forces, especially 45°, with the highest normal force of 77.95 N. Surface roughness analysis shows 90° orientation results in the lowest average roughness (Ra) of 10.97 µm but the highest surface roughness (Sa) of 34.25 µm. Conversely, 45° orientation has the highest Ra of 14.2 µm but lower Sa of 22.6 µm. Ra and Sa values for 0° orientation are 13.72 µm and 24.6 µm, and for −45° orientation, they are 12.3 µm and 21.8 µm. Correlation analysis reveals significant relationships between cutting parameters and surface quality, with higher feed rates correlating with smoother surfaces (lower Sa and Ra values). Fiber orientation also significantly influences fluffing defects, with 0° orientation minimizing these defects, while 45° and −45° orientations result in varied patterns.
亚麻/环氧复合材料被认为是工程领域合成纤维的环保替代品。了解纤维取向如何影响切削力和表面特性对加工这些材料至关重要。本研究调查了纤维取向与亚麻/环氧复合材料的切削力（进给力、法向力、被动力）以及表面粗糙度之间的关系。结果表明，纤维取向对切削力有很大影响。与纤维平行的切割（0° 和 90°）通常需要较小的力，0° 需要较大的法向力。表面粗糙度分析表明，90° 方向的平均粗糙度 (Ra) 最低，为 10.97 µm，但表面粗糙度 (Sa) 最高，为 34.25 µm。相反，45° 方向的 Ra 值最高，为 14.2 微米，但 Sa 值较低，为 22.6 微米。0° 方向的 Ra 值和 Sa 值分别为 13.72 微米和 24.6 微米，而 -45° 方向的 Ra 值和 Sa 值分别为 12.3 微米和 21.8 微米。相关分析表明，切削参数与表面质量之间存在显著关系，进给率越高，表面越光滑（Sa 和 Ra 值越低）。纤维取向对绒毛缺陷也有很大影响，0° 取向可将这些缺陷降至最低，而 45° 和 -45° 取向则会产生不同的缺陷。
{"title":"Impact of fiber orientation on cutting forces and surface quality in flax/epoxy composite machining","authors":"Mohamed Slamani, Hamza Chafai, Jean-François Chatelain","doi":"10.1177/00219983241271004","DOIUrl":"https://doi.org/10.1177/00219983241271004","url":null,"abstract":"Flax/epoxy composites are recognized as an eco-friendly alternative to synthetic fibers in engineering. Understanding how fiber orientation affects cutting forces and surface characteristics is essential for machining these materials. This study investigates the relationship between fiber orientation and cutting forces (feed, normal, passive) as well as surface roughness in flax/epoxy composites. Results show that fiber orientation significantly impacts cutting forces. Cutting parallel to fibers (0° and 90° orientations) generally requires less force, with 0° needing higher normal force. At 0° orientation, feed force is 46.47 N, normal force is 58.86 N, and passive force is 54.44 N. At 90° orientation, feed force is 56.66 N, normal force is 44.68 N, and passive force is 50.95 N. Oblique orientations (45° and −45°) require higher forces, especially 45°, with the highest normal force of 77.95 N. Surface roughness analysis shows 90° orientation results in the lowest average roughness (Ra) of 10.97 µm but the highest surface roughness (Sa) of 34.25 µm. Conversely, 45° orientation has the highest Ra of 14.2 µm but lower Sa of 22.6 µm. Ra and Sa values for 0° orientation are 13.72 µm and 24.6 µm, and for −45° orientation, they are 12.3 µm and 21.8 µm. Correlation analysis reveals significant relationships between cutting parameters and surface quality, with higher feed rates correlating with smoother surfaces (lower Sa and Ra values). Fiber orientation also significantly influences fluffing defects, with 0° orientation minimizing these defects, while 45° and −45° orientations result in varied patterns.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"22 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-31DOI: 10.1177/00219983241268895
Hong Ma, Robert S Pierce, Justine Beauson
To address the residual stress induced during the cure of fibre reinforced thermoset polymer composites, two different approaches were suggested for coupling a non-dominated sorting genetic algorithm (NSGA-II) with finite element (FE) simulations based on a viscoelastic constitutive law. These two approaches were proposed with consideration of different ways of integrating NSGA-II and the FE model. In Approach A, NSGA-II was performed based on results from a series of simulations under various combinations of cure variables. Alternatively, Approach B employed NSGA-II to iteratively update and optimise the cure profile for subsequent simulations. Results indicated that both approaches achieved simultaneous reductions in cure time and macroscale residual stress, with Approach B showing further improvements due to the direct coupling between the NSGA-II and simulations. Specifically, the maximum residual stress and cure time optimised by Approach A were reduced by 5%–9% and 22%–50% respectively, while those obtained by Approach B were reduced by 7%–10% and 32%–49% respectively, compared to those based on the manufacturer recommended cure profile. The evolution of stress in composites based on optimised cure profiles from these two approaches was also elucidated. Additionally, microscale modelling further revealed a 3%–5% reduction in the average residual stress within a representative volume element (RVE) model was also shown, depending upon the approach adopted. Ultimately, by combining a NSGA-II and FE simulations, the optimisation of cure time and residual stress at the macroscale and cure time together with a reduction of microscale stress could be realised.
为解决纤维增强热固性聚合物复合材料固化过程中引起的残余应力问题，建议采用两种不同的方法，将非优势排序遗传算法（NSGA-II）与基于粘弹性结构定律的有限元（FE）模拟相结合。提出这两种方法时，考虑了将 NSGA-II 与有限元模型相结合的不同方式。在方法 A 中，NSGA-II 是根据在各种固化变量组合下的一系列模拟结果来执行的。另外，方法 B 采用 NSGA-II 来迭代更新和优化后续模拟的固化曲线。结果表明，这两种方法都能同时减少固化时间和宏观残余应力，而方法 B 则由于 NSGA-II 与模拟之间的直接耦合而有了进一步的改进。具体来说，与制造商推荐的固化曲线相比，方法 A 优化的最大残余应力和固化时间分别减少了 5%-9%和 22%-50%，而方法 B 获得的最大残余应力和固化时间分别减少了 7%-10%和 32%-49%。根据这两种方法优化的固化曲线，复合材料的应力演变也得到了阐明。此外，微观建模进一步显示，根据所采用的方法，代表性体积元素（RVE）模型内的平均残余应力也降低了 3%-5%。最终，通过将 NSGA-II 和 FE 模拟相结合，可以优化宏观尺度的固化时间和残余应力，并在减少微观应力的同时缩短固化时间。
{"title":"Optimisation of process-induced residual stresses in composite laminates by different genetic algorithm and finite element simulation coupling methods","authors":"Hong Ma, Robert S Pierce, Justine Beauson","doi":"10.1177/00219983241268895","DOIUrl":"https://doi.org/10.1177/00219983241268895","url":null,"abstract":"To address the residual stress induced during the cure of fibre reinforced thermoset polymer composites, two different approaches were suggested for coupling a non-dominated sorting genetic algorithm (NSGA-II) with finite element (FE) simulations based on a viscoelastic constitutive law. These two approaches were proposed with consideration of different ways of integrating NSGA-II and the FE model. In Approach A, NSGA-II was performed based on results from a series of simulations under various combinations of cure variables. Alternatively, Approach B employed NSGA-II to iteratively update and optimise the cure profile for subsequent simulations. Results indicated that both approaches achieved simultaneous reductions in cure time and macroscale residual stress, with Approach B showing further improvements due to the direct coupling between the NSGA-II and simulations. Specifically, the maximum residual stress and cure time optimised by Approach A were reduced by 5%–9% and 22%–50% respectively, while those obtained by Approach B were reduced by 7%–10% and 32%–49% respectively, compared to those based on the manufacturer recommended cure profile. The evolution of stress in composites based on optimised cure profiles from these two approaches was also elucidated. Additionally, microscale modelling further revealed a 3%–5% reduction in the average residual stress within a representative volume element (RVE) model was also shown, depending upon the approach adopted. Ultimately, by combining a NSGA-II and FE simulations, the optimisation of cure time and residual stress at the macroscale and cure time together with a reduction of microscale stress could be realised.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"262 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-31DOI: 10.1177/00219983241270992
Hamzeh Shahrajabian, Hosein Vaezzadeh
More than 50% of the flame retardants used in the polymer and plastic industries are metal hydroxides. Among them, aluminum trihydroxide (ATH) is the most widely used due to its low toxicity and corrosiveness and its cost-effectiveness. The use of high-volume ATH in polymers reduces the mechanical properties. In this work, clay nanoparticles were added into epoxy/glass fiber/ATH hybrid composites to improve the mechanical and thermal properties of the composites. The effect of nano-clay content (1, 3, and 5 phr) on mechanical properties such as tensile and flexural strength and modulus, and thermal properties was investigated. Thermal properties were evaluated by Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). The result of mechanical tests showed that adding 3 phr of clay nanoparticles increases tensile and flexural strength by 10% and 9.2%, respectively. The flammability of the composites was measured in horizontal mode. The flammability results revealed that introducing 3 phr of nano-clay improves the flammability of the composites by 41%.
{"title":"The nano-clay effect on the improvement of the thermal, flammability, and mechanical behavior of epoxy/glass fiber/ATH hybrid composites","authors":"Hamzeh Shahrajabian, Hosein Vaezzadeh","doi":"10.1177/00219983241270992","DOIUrl":"https://doi.org/10.1177/00219983241270992","url":null,"abstract":"More than 50% of the flame retardants used in the polymer and plastic industries are metal hydroxides. Among them, aluminum trihydroxide (ATH) is the most widely used due to its low toxicity and corrosiveness and its cost-effectiveness. The use of high-volume ATH in polymers reduces the mechanical properties. In this work, clay nanoparticles were added into epoxy/glass fiber/ATH hybrid composites to improve the mechanical and thermal properties of the composites. The effect of nano-clay content (1, 3, and 5 phr) on mechanical properties such as tensile and flexural strength and modulus, and thermal properties was investigated. Thermal properties were evaluated by Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). The result of mechanical tests showed that adding 3 phr of clay nanoparticles increases tensile and flexural strength by 10% and 9.2%, respectively. The flammability of the composites was measured in horizontal mode. The flammability results revealed that introducing 3 phr of nano-clay improves the flammability of the composites by 41%.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"74 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-30DOI: 10.1177/00219983241268861
Norbert Geier, Gergely Magyar, Jakob Giner, Tamás Lukács, György Póka
Mechanical and thermodynamical properties and thus machinability of carbon fibre reinforced polymer composites significantly depend on the fibre orientation relative to the load direction. However, the orientations of the fibre groups in polymer composites reinforced by chopped carbon fibres are stochastic; therefore, the properties and machinability of such composites are challenging to plan, predict and optimise. We developed four different and novel approaches for fibre detection in polymer composites reinforced by chopped carbon fibres: (i) detecting the fibres through naked eye supported manual drawing, (ii) digital image processing of optical images, (iii) machine learning-based fibre detection, and (iv) rectangle fitting on the outputs of the automated processes using the Chaudhuri and Samal method. The applicability of the novel approaches was tested through optically captured images of polymer composites reinforced by chopped carbon fibres. The developed methods are each capable of detecting fibre groups at the top and bottom of the composite plate with certain limitations. The rectangle fitting approaches performed the best from the point of view of correctly identifying of fibre groups, followed by the machine learning-based and the conventional digital image processed, respectively. As a result of this study, the machining process planning and condition monitoring of polymer composites reinforced by chopped carbon fibres is more deeply supported.
碳纤维增强聚合物复合材料的机械性能和热力学性能以及加工性能在很大程度上取决于纤维相对于载荷方向的取向。然而，切碎碳纤维增强聚合物复合材料中纤维组的取向是随机的；因此，规划、预测和优化此类复合材料的性能和可加工性具有挑战性。我们开发了四种不同的新型方法，用于检测用切碎碳纤维增强的聚合物复合材料中的纤维：(i) 通过肉眼检测纤维，支持手工绘图；(ii) 光学图像的数字图像处理；(iii) 基于机器学习的纤维检测；(iv) 使用 Chaudhuri 和 Samal 方法对自动化流程的输出进行矩形拟合。通过光学捕捉到的切碎碳纤维增强聚合物复合材料图像，测试了这些新方法的适用性。所开发的方法都能检测到复合板顶部和底部的纤维组，但有一定的局限性。从正确识别纤维组的角度来看，矩形拟合方法的效果最好，其次分别是基于机器学习的方法和传统的数字图像处理方法。这项研究为切碎碳纤维增强聚合物复合材料的加工工艺规划和状态监测提供了更深入的支持。
{"title":"Carbon fibre detection in polymer composites reinforced by chopped carbon fibres through digital image processing and machine learning","authors":"Norbert Geier, Gergely Magyar, Jakob Giner, Tamás Lukács, György Póka","doi":"10.1177/00219983241268861","DOIUrl":"https://doi.org/10.1177/00219983241268861","url":null,"abstract":"Mechanical and thermodynamical properties and thus machinability of carbon fibre reinforced polymer composites significantly depend on the fibre orientation relative to the load direction. However, the orientations of the fibre groups in polymer composites reinforced by chopped carbon fibres are stochastic; therefore, the properties and machinability of such composites are challenging to plan, predict and optimise. We developed four different and novel approaches for fibre detection in polymer composites reinforced by chopped carbon fibres: (i) detecting the fibres through naked eye supported manual drawing, (ii) digital image processing of optical images, (iii) machine learning-based fibre detection, and (iv) rectangle fitting on the outputs of the automated processes using the Chaudhuri and Samal method. The applicability of the novel approaches was tested through optically captured images of polymer composites reinforced by chopped carbon fibres. The developed methods are each capable of detecting fibre groups at the top and bottom of the composite plate with certain limitations. The rectangle fitting approaches performed the best from the point of view of correctly identifying of fibre groups, followed by the machine learning-based and the conventional digital image processed, respectively. As a result of this study, the machining process planning and condition monitoring of polymer composites reinforced by chopped carbon fibres is more deeply supported.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"25 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-30DOI: 10.1177/00219983241268898
Soma A. El Mogy, Hanan Mohamed Eyssa, Rasha Mohammad Fathy, Mahmoud Hamdi Sanad
Infective diseases are becoming more popular, and managing them has become a great worry for humanity. A rubber nanocomposite based on nitrile butadiene rubber with graphene oxide (NBR/GO) and GO/nanoclay (montmorillonite, MMT) (NBR/GO/MMT) was fabricated by a simple technique, roll milling. The synergistic influence of the existence of GO, clay, and electron beam (EB)-radiation on the NBR nanocomposites was characterized using scanning electron microscopy (SEM), and Fourier-transform infrared (FT–IR) techniques to study the mechanical, thermal, and antibacterial properties. The antibacterial activity of the prepared rubber nanocomposites was estimated via the disk diffusion process against Gram-positive bacteria, Bacillus subtilis, Staphylococcus lentus, and Gram-negative bacteria ; Pseudomonas aeruginosa and Proteus mirabilis. The results demonstrated that the physico-mechanical performance was significantly reinforced by incorporating nano GO (6 phr) and clay with GO (3 phr/6 phr. NBR films have no antibacterial potential. GO increases the antibacterial efficiency of the NBR films. NBR/3% GO/3% clay film is the most effective in reducing bacterial growth and B. subtilis was the most sensitive bacteria for rubber treatments. The inhibition zone diameters of the un-irradiated and irradiated NBR/3% GO/3% clay films for B. subtilis were 18.03 ± 0.59 and 25.63 ± 0.98 mm, respectively. It could be concluded that because of its outstanding flexibility and human-body compatibility penetration, rubber in corporation with antimicrobial agents can be utilized for manufacturing medical and environmental products.
{"title":"Dual influence of graphene oxide/clay and electron beam radiation on the structure, mechanical, thermal, and antimicrobial properties of nitrile butadiene rubber nanocomposite","authors":"Soma A. El Mogy, Hanan Mohamed Eyssa, Rasha Mohammad Fathy, Mahmoud Hamdi Sanad","doi":"10.1177/00219983241268898","DOIUrl":"https://doi.org/10.1177/00219983241268898","url":null,"abstract":"Infective diseases are becoming more popular, and managing them has become a great worry for humanity. A rubber nanocomposite based on nitrile butadiene rubber with graphene oxide (NBR/GO) and GO/nanoclay (montmorillonite, MMT) (NBR/GO/MMT) was fabricated by a simple technique, roll milling. The synergistic influence of the existence of GO, clay, and electron beam (EB)-radiation on the NBR nanocomposites was characterized using scanning electron microscopy (SEM), and Fourier-transform infrared (FT–IR) techniques to study the mechanical, thermal, and antibacterial properties. The antibacterial activity of the prepared rubber nanocomposites was estimated via the disk diffusion process against Gram-positive bacteria, Bacillus subtilis, Staphylococcus lentus, and Gram-negative bacteria ; Pseudomonas aeruginosa and Proteus mirabilis. The results demonstrated that the physico-mechanical performance was significantly reinforced by incorporating nano GO (6 phr) and clay with GO (3 phr/6 phr. NBR films have no antibacterial potential. GO increases the antibacterial efficiency of the NBR films. NBR/3% GO/3% clay film is the most effective in reducing bacterial growth and B. subtilis was the most sensitive bacteria for rubber treatments. The inhibition zone diameters of the un-irradiated and irradiated NBR/3% GO/3% clay films for B. subtilis were 18.03 ± 0.59 and 25.63 ± 0.98 mm, respectively. It could be concluded that because of its outstanding flexibility and human-body compatibility penetration, rubber in corporation with antimicrobial agents can be utilized for manufacturing medical and environmental products.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"358 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1177/00219983241265922
Hossein Malekinejad, Amin Farrokhabadi, Gholam Hossein Rahimi, Ricardo Carbas, Eduardo AS Marques, Lucas da Silva
Sandwich structures are often prone to catastrophic failure due to premature separation between the core and skin layers. Geometric parameters, such as the thickness of the skin and core, along with the materials used in their manufacturing, directly influence the resistance to separation between the skin and core. This study explores how variations in skin thickness affect both failure modes and maximum load capacity in sandwich structures, utilizing both experimental testing and numerical simulations. Specimens were categorized as intact and pre-debonded samples. Each specimen featured four different skin thicknesses (3, 6, 8, and 10 layers of composite laminated skins, with corresponding thicknesses of 0.68, 1.33, 1.73, and 2.1 mm respectively). The specimens incorporated a foam-filled square corrugated core and underwent 3-point bending tests. Results revealed a significant shift in the failure mode: initially observed as upper skin fracture (V-shaped failure), it transitioned to separation between skins and cores with increased skin thickness, particularly in the presence of pre-debonding. Notably, the predominant failure mode did not involve separation between the skin and core in specimens without a pre-existing crack. Furthermore, numerical simulations effectively demonstrated the accurate capture of failure modes and loads using the Hashin and cohesive zone model (CZM).
{"title":"Skin thickness effects on failure mechanisms in foam infilled composite sandwich structures","authors":"Hossein Malekinejad, Amin Farrokhabadi, Gholam Hossein Rahimi, Ricardo Carbas, Eduardo AS Marques, Lucas da Silva","doi":"10.1177/00219983241265922","DOIUrl":"https://doi.org/10.1177/00219983241265922","url":null,"abstract":"Sandwich structures are often prone to catastrophic failure due to premature separation between the core and skin layers. Geometric parameters, such as the thickness of the skin and core, along with the materials used in their manufacturing, directly influence the resistance to separation between the skin and core. This study explores how variations in skin thickness affect both failure modes and maximum load capacity in sandwich structures, utilizing both experimental testing and numerical simulations. Specimens were categorized as intact and pre-debonded samples. Each specimen featured four different skin thicknesses (3, 6, 8, and 10 layers of composite laminated skins, with corresponding thicknesses of 0.68, 1.33, 1.73, and 2.1 mm respectively). The specimens incorporated a foam-filled square corrugated core and underwent 3-point bending tests. Results revealed a significant shift in the failure mode: initially observed as upper skin fracture (V-shaped failure), it transitioned to separation between skins and cores with increased skin thickness, particularly in the presence of pre-debonding. Notably, the predominant failure mode did not involve separation between the skin and core in specimens without a pre-existing crack. Furthermore, numerical simulations effectively demonstrated the accurate capture of failure modes and loads using the Hashin and cohesive zone model (CZM).","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"56 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141523752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-22DOI: 10.1177/00219983241262955
Josef Koord, Christian Hühne
Hybrdization of CFRP with steel sheets enhances bolt-bearing performance. At room temperature, bearing strength is reported to increase while minimum edge and width distances decrease. To assess if this advantage persists under low temperature conditions, bolt-bearing tests following AITM 1-0009 are conducted at 23°C and −55°C. Various monolithic and hybrid configurations with different metal content and joint geometries are examined. Furthermore, ultrasound scanning and optical microscopy of the fracture plane is conducted. Hybridizing composites notably improves bearing capacity. However, the reinforcement effect is less pronounced at low temperatures compared to room temperature. The reduction in minimum edge and width distances with metal hybridization largely depends on the composite ply stacking, challenging general literature recommendations. Regarding damage mechanisms in the joints, fractography indicates that introduction of steel sheets relieves composite plies, isolates damage, and enhances load-bearing capacity through additional bending stiffness and significant plastic deformation of the metal.
{"title":"Bolt-bearing behavior of hybrid CFRP-steel laminates at low temperature","authors":"Josef Koord, Christian Hühne","doi":"10.1177/00219983241262955","DOIUrl":"https://doi.org/10.1177/00219983241262955","url":null,"abstract":"Hybrdization of CFRP with steel sheets enhances bolt-bearing performance. At room temperature, bearing strength is reported to increase while minimum edge and width distances decrease. To assess if this advantage persists under low temperature conditions, bolt-bearing tests following AITM 1-0009 are conducted at 23°C and −55°C. Various monolithic and hybrid configurations with different metal content and joint geometries are examined. Furthermore, ultrasound scanning and optical microscopy of the fracture plane is conducted. Hybridizing composites notably improves bearing capacity. However, the reinforcement effect is less pronounced at low temperatures compared to room temperature. The reduction in minimum edge and width distances with metal hybridization largely depends on the composite ply stacking, challenging general literature recommendations. Regarding damage mechanisms in the joints, fractography indicates that introduction of steel sheets relieves composite plies, isolates damage, and enhances load-bearing capacity through additional bending stiffness and significant plastic deformation of the metal.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"40 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-21DOI: 10.1177/00219983241264364
Malihe Rahnama, S Reza Hamzeloo, Mohammad Morad Sheikhi
Drawing upon both theoretical and experimental methodologies, this study investigates the vibrational characteristics of lattice sandwich truncated conical shells featuring composite ribs made of carbon and E-glass fibers. Toward this aim, the equations of motion along with the corresponding boundary conditions of such sandwich shells are derived using classical Donnell’s shell theory and the smeared stiffness technique. Subsequently, the governing equations are solved to obtain a closed-form expression for natural frequencies employing the Galerkin method. In addition, ABAQUS simulations are presented to study the vibration behavior of single-skin and three-skin conical shells. To validate the theoretical methods, the specimens of three-layer sandwich conical shells were fabricated from two Kevlar fabric laminates and a composite lattice core with hexagonal cells using a manual filament winding process. The composite ribs consist of carbon and E-glass fibers with a ratio of 3:1. Finally, experimental modal tests were conducted to extract natural frequencies and mode shapes by measuring frequency responses at 40 points over a duration of 60 s using a laser vibrometer. A strong correspondence is observed between the theoretical outcomes (utilizing the Galerkin and FE methods) and the experimental findings (with a maximum discrepancy of approximately 16% for the initial four mode shapes). Findings indicate that the excellent performance of the composite lattice core in vibration behavior, which can increase approximately 19% and 16% the natural frequencies corresponding to the first and second mode shapes, respectively.
本研究利用理论和实验方法，研究了以碳纤维和 E 玻璃纤维复合肋为特征的晶格夹层截顶锥形壳的振动特性。为此，利用经典的唐奈壳理论和涂抹刚度技术推导出了这种夹层壳的运动方程和相应的边界条件。随后，利用 Galerkin 方法求解了支配方程，得到了固有频率的闭式表达式。此外，还介绍了 ABAQUS 仿真，以研究单层和三层锥壳的振动行为。为验证理论方法，采用手动绕丝工艺，用两层凯夫拉纤维层压板和六角形单元的复合网格芯制成了三层夹层锥形壳体试件。复合材料肋条由碳纤维和 E 玻璃纤维组成，比例为 3:1。最后，通过使用激光测振仪在 60 秒内测量 40 个点的频率响应，进行了实验模态测试，以提取固有频率和模态振型。理论结果（利用 Galerkin 和 FE 方法）与实验结果（初始四种模态振型的最大差异约为 16%）之间具有很强的对应性。研究结果表明，复合材料晶格核心在振动行为方面表现出色，可将第一和第二模态振型对应的固有频率分别提高约 19% 和 16%。
{"title":"Vibration analysis of anisogrid composite lattice sandwich truncated conical shells: Theoretical and experimental approaches","authors":"Malihe Rahnama, S Reza Hamzeloo, Mohammad Morad Sheikhi","doi":"10.1177/00219983241264364","DOIUrl":"https://doi.org/10.1177/00219983241264364","url":null,"abstract":"Drawing upon both theoretical and experimental methodologies, this study investigates the vibrational characteristics of lattice sandwich truncated conical shells featuring composite ribs made of carbon and E-glass fibers. Toward this aim, the equations of motion along with the corresponding boundary conditions of such sandwich shells are derived using classical Donnell’s shell theory and the smeared stiffness technique. Subsequently, the governing equations are solved to obtain a closed-form expression for natural frequencies employing the Galerkin method. In addition, ABAQUS simulations are presented to study the vibration behavior of single-skin and three-skin conical shells. To validate the theoretical methods, the specimens of three-layer sandwich conical shells were fabricated from two Kevlar fabric laminates and a composite lattice core with hexagonal cells using a manual filament winding process. The composite ribs consist of carbon and E-glass fibers with a ratio of 3:1. Finally, experimental modal tests were conducted to extract natural frequencies and mode shapes by measuring frequency responses at 40 points over a duration of 60 s using a laser vibrometer. A strong correspondence is observed between the theoretical outcomes (utilizing the Galerkin and FE methods) and the experimental findings (with a maximum discrepancy of approximately 16% for the initial four mode shapes). Findings indicate that the excellent performance of the composite lattice core in vibration behavior, which can increase approximately 19% and 16% the natural frequencies corresponding to the first and second mode shapes, respectively.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"22 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the primary challenges faced by sandwich composites is facesheet-core debonding, which can be mitigated through various techniques such as z-pinning and stitching through the thickness. This study investigates the impact of stitching on the bending behavior of sandwich composites comprising E-glass composite facesheets and a polyurethane foam core, employing experimental, numerical, and analytical methods. Specimens were stitched at three stitch spacings of 0.5, 1, and 2 cm, with a stitch pitch of 0.8 cm and stitch seam angles of 0°, 90°, 0/90°, ±45°, 45°/90°, and ±60°. Analysis of facesheet bending stress, core shear stress, and bending rigidity of stitched specimens was conducted through three-point bending tests and compared with unstitched specimens. Results indicate that reducing stitch spacing, thereby increasing stitch density, improves bending strength, and the best bending behavior observed at ±45° stitch seam angles. Damage assessment revealed fractures and depression of the foam, wrinkles on the upper facesheet, and buckling failure of resin columns. Additionally, a theoretical model predicted bending rigidity, showing good agreement (4%–15%) with experimental data. Finite element analysis using the ABAQUS program validated the experimental results, suggesting numerical modeling as a viable method for predicting flexural properties of stitched foam core sandwich composites.
夹层复合材料面临的主要挑战之一是面片与夹芯的脱粘，可通过各种技术来缓解这一问题，例如通过厚度进行 Z 形钉合和缝合。本研究采用实验、数值和分析方法，研究了缝合对由 E 玻璃复合材料面板和聚氨酯泡沫夹芯组成的夹层复合材料弯曲行为的影响。试样按 0.5、1 和 2 厘米三种缝合间距缝合，缝合间距为 0.8 厘米，缝合角度为 0°、90°、0/90°、±45°、45°/90° 和 ±60°。通过三点弯曲试验分析了缝合试样的面板弯曲应力、核心剪应力和弯曲刚度，并与未缝合试样进行了比较。结果表明，减少缝合间距从而增加缝合密度可提高弯曲强度，在 ±45° 缝合角处可观察到最佳弯曲性能。损伤评估显示，泡沫出现断裂和凹陷，上面板出现皱纹，树脂柱出现屈曲失效。此外，理论模型预测了弯曲刚度，结果与实验数据吻合（4%-15%）。使用 ABAQUS 程序进行的有限元分析验证了实验结果，表明数值建模是预测缝合泡沫夹芯复合材料弯曲性能的一种可行方法。
{"title":"Effects of stitching parameters on the flexural properties of stitched foam core sandwich composites","authors":"Shekoufeh Rasouli Rizi, Hooshang Nosraty, Seyed Abolfazl Mirdehghan","doi":"10.1177/00219983241265165","DOIUrl":"https://doi.org/10.1177/00219983241265165","url":null,"abstract":"One of the primary challenges faced by sandwich composites is facesheet-core debonding, which can be mitigated through various techniques such as z-pinning and stitching through the thickness. This study investigates the impact of stitching on the bending behavior of sandwich composites comprising E-glass composite facesheets and a polyurethane foam core, employing experimental, numerical, and analytical methods. Specimens were stitched at three stitch spacings of 0.5, 1, and 2 cm, with a stitch pitch of 0.8 cm and stitch seam angles of 0°, 90°, 0/90°, ±45°, 45°/90°, and ±60°. Analysis of facesheet bending stress, core shear stress, and bending rigidity of stitched specimens was conducted through three-point bending tests and compared with unstitched specimens. Results indicate that reducing stitch spacing, thereby increasing stitch density, improves bending strength, and the best bending behavior observed at ±45° stitch seam angles. Damage assessment revealed fractures and depression of the foam, wrinkles on the upper facesheet, and buckling failure of resin columns. Additionally, a theoretical model predicted bending rigidity, showing good agreement (4%–15%) with experimental data. Finite element analysis using the ABAQUS program validated the experimental results, suggesting numerical modeling as a viable method for predicting flexural properties of stitched foam core sandwich composites.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"4 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.1177/00219983241260555
Mariam A. Al-Dhaheri, Wesley J. Cantwell, Imad Barsoum, Rehan Umer
In this study, the Time-Temperature-Crystallinity Superposition Principle (TTCSP) was applied to determine the viscoelastic behavior of Thermo-rheological Complex Materials (TCM), specifically Carbon fibre/Poly-Ether-Ketone-Ketone (CF/PEKK) composites. The study investigated the effects of various parameters on the viscoelastic behavior of the composites, such as the degree of crystallinity after different melting temperatures, relaxation, and crystallization times. The TTCSP was utilized on the relaxation data to generate great-grand master curves for the degree of crystallinity for different laminate lay-ups. Hot press forming was employed to manufacture samples under different processing conditions, including various melting and cold crystallization temperatures. Differential Scanning Calorimetry (DSC) was employed to calculate the degree of crystallinity of CF/PEKK composites, while the Dynamic Mechanical Analyzer (DMA) was used to obtain the relaxation data. The generated great-grand master curves proved effective in predicting the relaxation behavior of the composites consolidated using single and double hold cycles at different melting temperatures and crystallization times, respectively. The great-grand master curves presented in this study can serve as valuable tool to calibrate key viscoelastic and/or thermo-viscoelastic material models for aerospace-grade CF/PEKK composites. These models are crucial for simulations aimed at predicting residual stresses and process-induced deformations during the thermoforming process.
{"title":"Characterization of relaxation behaviour of CF/PEKK aerospace composites using the time-temperature-crystallinity superposition principle","authors":"Mariam A. Al-Dhaheri, Wesley J. Cantwell, Imad Barsoum, Rehan Umer","doi":"10.1177/00219983241260555","DOIUrl":"https://doi.org/10.1177/00219983241260555","url":null,"abstract":"In this study, the Time-Temperature-Crystallinity Superposition Principle (TTCSP) was applied to determine the viscoelastic behavior of Thermo-rheological Complex Materials (TCM), specifically Carbon fibre/Poly-Ether-Ketone-Ketone (CF/PEKK) composites. The study investigated the effects of various parameters on the viscoelastic behavior of the composites, such as the degree of crystallinity after different melting temperatures, relaxation, and crystallization times. The TTCSP was utilized on the relaxation data to generate great-grand master curves for the degree of crystallinity for different laminate lay-ups. Hot press forming was employed to manufacture samples under different processing conditions, including various melting and cold crystallization temperatures. Differential Scanning Calorimetry (DSC) was employed to calculate the degree of crystallinity of CF/PEKK composites, while the Dynamic Mechanical Analyzer (DMA) was used to obtain the relaxation data. The generated great-grand master curves proved effective in predicting the relaxation behavior of the composites consolidated using single and double hold cycles at different melting temperatures and crystallization times, respectively. The great-grand master curves presented in this study can serve as valuable tool to calibrate key viscoelastic and/or thermo-viscoelastic material models for aerospace-grade CF/PEKK composites. These models are crucial for simulations aimed at predicting residual stresses and process-induced deformations during the thermoforming process.","PeriodicalId":15489,"journal":{"name":"Journal of Composite Materials","volume":"37 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141196640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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