Article
Materials Science, Composites
Zhe Che, Min Li, Shuo Wang, Shaokai Wang, Yizhuo Gu, Wei Zhang
Summary: This study improves the shear delamination resistance of composite laminate and enhances crack propagation resistance by using fine z-pins. The results demonstrate that z-pinning plays a significant role in improving interlaminar fracture toughness, and decreasing the z-pin diameter further enhances the resistance to crack propagation.
POLYMER COMPOSITES
(2022)
Article
Engineering, Manufacturing
E. Santana de Vega, G. Allegri, B. Zhang, I. Hamerton, S. R. Hallett
Summary: This paper presents a characterization of the effect of varying the polymer matrix in Z-pin through-thickness reinforcement in pre-preg based laminates. The experimental results indicate that Z-pins with a high elongation at break, such as LTG Z-pins, exhibit superior bridging performance and toughness.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2022)
Article
Materials Science, Multidisciplinary
Min Li, Zhe Che, Shaokai Wang, Yubo Zhou, Hao Fu, Yizhuo Gu, Wei Zhang
Summary: By implanting fine z-pins on the in-plane fibers, the interlaminar fracture toughness of carbon fiber reinforced polymer (CFRP) composites can be significantly improved, while maintaining high retentions of in-plane mechanical properties. The mechanical properties of the carbon fiber pins play a crucial role in enhancing the composite laminate.
MATERIALS & DESIGN
(2021)
Article
Materials Science, Composites
Bing Zhang, Stephen R. Hallett, Giuliano Allegri
Summary: This paper explores a novel technique for sensing delamination in through-thickness reinforced composites using electromagnetic induction. By utilizing ferromagnetic Z-pins and coils, this method is able to avoid potential interferences from contact electrical resistances and has been demonstrated to be viable in bridging tests. The sensitivity of the magnetic-based sensing technique increases with loading rate and is capable of detecting both mode I and mode II delamination events.
COMPOSITES SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Mechanical
Imad Hanhan, Alejandra M. Ortiz-Morales, Jose Javier Solano, Michael D. Sangid
Summary: A compact tension T650/5320 laminate composite was characterized using in-situ X-ray tomography to analyze the damage mechanisms during cyclic loading. The 3D image processing analysis revealed the presence of intralaminar cracking and delamination facilitating ply cross-over. A finite element analysis was conducted to compute the change in stored energy per cycle, dU/dN, which showed that the observed intralaminar crack growth rates collapsed to a single curve.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Mechanics
Andre Knopp, Elisabeth Funck, Andreas Holtz, Gerhard Scharr
Summary: The investigations conducted in this study demonstrate that the properties of z-pin reinforced laminates can be positively influenced by using circumferentially notches as a defined z-pin surface micro-structuring. The fracture mechanical properties under Mode-I crack opening loading can be significantly improved and the resulting delamination areas that occur during an impact can be effectively reduced. The residual strength properties of pinned laminates are also more favorable and can be further enhanced with the use of circumferentially notched z-pins.
COMPOSITE STRUCTURES
(2022)
Article
Engineering, Civil
Xuebei Teng, Yingjie Xu, Weihong Zhang, Weiwei Liu, Mingxin Yin
Summary: In this study, the resistance of delamination in curved carbon fiber/epoxy composite laminates reinforced by z-pins was experimentally investigated. A cost-effective pre-hole z-pinning technique was applied to mitigate initial in-plane damage, and the effect of z-pin volume fraction and diameter on interlaminar fracture toughness and bridging behavior was evaluated through double cantilever beam testing. The mode-mixity of z-pin was determined, and the fracture toughness of curved specimens was calculated based on Timoshenko curved beam theory. The results showed that the mode-mixity varied depending on the location of z-pins, and z-pins experienced a combination of crack opening and crack sliding loads during the tests. The primary failure mode of z-pins was pull-out, with a minor portion experiencing fracture. The fracture toughness of specimens with 0.8 vol% z-pins was significantly higher compared to unpinned specimens, indicating the delamination resistance capacity of z-pins was influenced by the mixed-mode ratio.
THIN-WALLED STRUCTURES
(2023)
Article
Engineering, Manufacturing
T. W. Loh, R. B. Ladani, A. Ravindran, R. Das, E. Kandare, A. P. Mouritz
Summary: The addition of thermoplastic mendable filaments in z-pinned composites can greatly increase interlaminar fracture toughness, repair delamination damage, and enhance crack propagation resistance. This novel repair process has the potential application for various types of composites with through-thickness reinforcement.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2021)
Article
Engineering, Manufacturing
Mathew W. Joosten, Carlos G. Davila, Qingda Yang
Summary: A computationally efficient fatigue analysis methodology is proposed that can predict the initiation and propagation of cracks using a cycle jump approach and a unified local fatigue cohesive zone model. The results of verification and validation experiments indicate that this method can reproduce fatigue damage initiation and evolution for different configurations and load combinations.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2022)
Article
Mechanics
Liaojun Yao, Hao Cui, Licheng Guo, Yi Sun
Summary: A new total fatigue life model for delamination growth in composites has been proposed in this study, which can appropriately characterize the FDG behavior under various fatigue loading conditions. By obtaining master resistance curves, the FDG behavior under different R-ratios can be determined, with these curves shifting downwards with mode mixity changes.
COMPOSITE STRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
L. Huo, C. Kassapoglou, R. C. Alderliesten
Summary: In order to improve the current design approaches for composite structures, further investigation is needed on the damage interaction effects of composite materials under multiple out-of-plane concentrated loads. A combined experimental and numerical study was conducted, where two sequential out-of-plane quasi-static indentations were applied to fully clamped composite laminated panels. The results show that the second indentation delamination is more likely to propagate, indicating a decrease in the effective delamination threshold associated with microcracks ahead of the delamination front.
MATERIALS & DESIGN
(2023)
Article
Engineering, Manufacturing
S. Abbasi, R. B. Ladani, C. H. Wang, A. P. Mouritz
Summary: The study investigates the mechanisms and effectiveness of metallic and composite z-filaments in improving the interlaminar fatigue resistance of fibre-polymer laminates. Results show that steel z-filaments are more effective than copper filaments in resisting fatigue crack initiation and growth under interlaminar cyclic loads. Differences in crack bridging efficiency under interlaminar fatigue loading contribute to the varying extents of improvement provided by the three filaments.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2021)
Article
Chemistry, Physical
Boyu Ju, Zhenhe Yu, Huasong Gou, Wenshu Yang, Guoqin Chen, Gaohui Wu
Summary: A new strategy to improve strength and ductility by coordinated deformation mechanism of multilayer graphene in graphene/aluminum composite was proposed.
Article
Polymer Science
Mariana Domnica Stanciu, Silviu Marian Nastac, Ionut Tesula
Summary: This paper focuses on the sensitivity analysis of the effects of delamination of fiberglass-reinforced polymer composites in wind turbine blade structures using finite element analysis. The research reveals that delamination affects the stress states of the blade, with maximum stress values depending on the orientation of the composite layers.
Article
Materials Science, Composites
Yusuf Polat, Bulent Ekici, Ali Kilic
Summary: The study showed that solution-blown nanofiber coatings improved the Mode-I fracture toughness of carbon fiber-reinforced epoxy composites by stabilizing crack propagation and increasing delamination strength. Dynamic mechanical analysis demonstrated that nanofibers increased material stiffness even with a small coating amount.
POLYMER COMPOSITES
(2021)
Article
Mechanics
Xiaolong Liu, Kelian Luo, Pengcheng Gao, Tao Cong, Xi Wang, Wenjing Wang
Summary: This paper investigates the formation mechanisms of the zig-zag crack region on the shattered rim of railway wheels. The zig-zag crack region, identified as a typical region for crack propagation in rolling contact fatigue behavior, was observed using scanning electron microscopy and transmission electron microscopy. The formation of the zig-zag morphology is attributed to the periodic deflection of the propagation path relative to the initial propagation plane, caused by the limited plastic deformation zone at the crack tip. Grain refinement and secondary cracks in the zig-zag crack region are a result of the large compressive and shear stresses induced by rolling contact loading.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Anastasia Iziumova, Aleksei Vshivkov, Ivan Panteleev, Virginia Mubassarova, Oleg Plekhov, Denis Davydov
Summary: The aim of this study was to investigate the correlation between structural, acoustic emission, and thermal characteristics of fatigue crack growth in titanium alloys. Cluster analysis of the acoustic emission signals revealed two different types of signals observed during the fatigue crack development. It was experimentally demonstrated that the stored energy tends to reach an asymptotic value at the final stage of fatigue crack growth and this is correlated with the twinning process intensification in titanium alloy Ti Grade 2. A correlation was assumed between the stages of change in heat flux, the cumulative energy of the first cluster of acoustic emission signals, and the crack length.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
M. Vieira de Carvalho, I. A. Rodrigues Lopes, F. M. Andrade Pires
Summary: This study investigates the numerical challenges of fracture mechanics models within implicit quasi-static frameworks and proposes an instability criterion. The ratio of cohesive to internal power is identified as a crucial factor. Two strategies for handling fracture problems with instabilities are discussed and a comparative assessment is performed. The study also examines more complex material responses, including transformation-induced plasticity effects.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Thomas Duminy, Aurelien Doitrand, Sylvain Meille
Summary: This study conducted in situ wedge splitting tests on millimeter-size PMMA samples and proposed a method to determine the material tensile strength and critical energy release rate using digital image correlation and a full finite element implementation of the coupled criterion.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Xin Chang, Xingyi Wang, Chunhe Yang, Yintong Guo, Yanghui Wan
Summary: The influence of cyclic thermal shock and high-temperature acid etching on the Mode I fracture of shale was investigated in this study. It was found that cyclic thermal shock severely degrades the strength and fracture toughness of shale, while high-temperature acid etching treatment improves the fracture toughness. These findings are valuable for optimizing process parameters to reduce initiation pressure in deep shale formations.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Liaojun Yao, Mingyue Chuai, Zhangming Lyu, Xiangming Chen, Licheng Guo, R. C. Alderliesten
Summary: Methods based on fracture mechanics have been widely used in fatigue delamination growth (FDG) characterization of composite laminates. This study proposes appropriate similitude parameters to represent FDG behavior with different R-ratios.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Zesheng Zang, Zhonghui Li, Yue Niu, Shan Yin
Summary: This study conducted experiments and recorded signals to investigate the fracture behavior and damage evolution characteristics of coal samples. The results showed that as loading proceeds, the stress, electric potential (EP), and acoustic emission (AE) values increase, and EP and AE signals are excited when stress drops. The fracture behavior of coal samples is altered by flaw inclination, and the destruction mode becomes increasingly complicated. The damage evolution characteristics of coal samples can be evaluated and analyzed by defining the coefficient of variation (CV value) of EP and the b value of AE.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Clotilde Berdin, Nathalie Prud'homme
Summary: In this study, zirconia layers with different fractions of tetragonal phase and thicknesses were tested for multi-cracking behavior. Cracks perpendicular to the tensile direction were observed, showing a blunting effect into the substrate. The ratio of crack spacing at saturation to layer thickness decreased as the layer thickness increased. Unit cell modeling was used to establish a relationship between crack spacing and layer strength, which fell within the bounds of Hu and Evans model and was found to be insensitive to the tetragonal zirconia fraction.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Huadong Zhang, Weichen Kong, Y. H. Liu, Yuh J. Chao
Summary: Williams' series expansion crack tip solution in linear elasticity is modified to include a uniform crack face pressure. Practical methods to calculate T-stress from near crack tip stresses are outlined. The analytical results are consistent with numerical results.
ENGINEERING FRACTURE MECHANICS
(2024)
Article
Mechanics
Jiahao Kong, Haoyue Han, Tao Wang, Guangyan Huang, Zhuo Zhuang
Summary: This paper introduces a phase-field model for polymer foam materials by combining the phase-field method with the crushable foam model. The model is calibrated using experimental data and successfully simulates the fracture processes of polyurethane under different loading conditions. The study is important for the engineering applications of polymer foam materials.
ENGINEERING FRACTURE MECHANICS
(2024)