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
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, Civil
Yu Gong, Kaixin Xia, Yana Wang, Libin Zhao, Jianyu Zhang, Ning Hu
Summary: This study establishes a semi-analytical model for determining the mode II fracture toughness of multidirectional laminates. The effects of interfacial angles on fracture toughness are investigated and the model has a clear correlation with the interfacial angles, showing good agreement with test results.
THIN-WALLED STRUCTURES
(2023)
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
Mechanics
Yu Gong, Xinjian Chen, Luohuan Zou, Xiangqian Li, Libin Zhao, Jianyu Zhang, Ning Hu
Summary: This study experimentally and numerically investigates the effect of different elastic moduli of z-pins on the delamination behavior of laminated composites. It is found that the elastic modulus affects the steady-state fracture toughness, bridging zone length, and micro failure mechanism.
COMPOSITE STRUCTURES
(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
Mechanics
Yue Liu, Gong-dong Wang, Yichao Shen, Ebo Blackie, Long He
Summary: A comprehensive experimental investigation was conducted to evaluate the toughening behavior of PES and CNTs interleaf in CFRP composites. The influence of four different environmental conditions on mode II fracture toughness (GIIC) was discussed. Results showed that CNTs and PES/CNT1 interleaves significantly enhanced the GIIC by 118.4% and 317.81% respectively, and the hybrid PES/CNTs interleaf exhibited higher mode II fracture toughness and greater adaptability to the environment. Experimental results and SEM images demonstrated the fracture behavior.
COMPOSITE STRUCTURES
(2023)
Article
Engineering, Multidisciplinary
M. Elhadary, A. Hamdy, W. Shaker
Summary: The study investigated the extrinsic non-autonomic self-healing of composite material in two cases of crack, with and without bridging phenomena. It was found that bridging significantly increased the efficiency of crack healing, demonstrating the importance of bridging in enhancing self-healing capabilities.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Chemistry, Physical
Christophe Floreani, Colin Robert, Parvez Alam, Peter Davies, Conchur M. O. Bradaigh
Summary: This study investigates the interlaminar fracture toughness, in-plane mechanical properties, and mixed-mode critical strain energy release rate of powder epoxy composites. The results show that the toughness of this material is significantly higher than that of other epoxy composites, making it suitable for manufacturing structures where there is a risk of delamination.
Article
Mechanics
Daniel Brighenti Bortoluzzi, Camila Aparecida Diniz, Joao Luiz Junho Pereira, Ronny Francis Ribeiro Junior, Guilherme Ferreira Gomes, Antonio Carlos Ancelotti Junior
Summary: This study is the first to use Artificial Neural Networks (ANN) to predict and assess the mode II interlaminar fracture toughness in z-pinned composites. Z-pins with different rectangular shapes and pin area densities are manufactured using design variables generated from Design of Experiments (DOE). The experimental results show an improvement in the mode II delamination resistance of z-pinned specimens compared to unpinned ones. Response Surface Model (RSM) and Analysis of Variance (ANOVA) are used for statistical analysis, and the generated data are used to train an Artificial Neural Network to predict and evaluate the influence of pin size and density configuration on interlaminar fracture properties of z-pinned composite structures.
COMPOSITE STRUCTURES
(2023)
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, Multidisciplinary
Philipp Hahn, Harichandana Channammagari, Mathieu Imbert, Michael May
Summary: This paper presents a novel high-rate transverse crack tension (TCT) test for determining mode II fracture toughness under high strain rates. The results show that the fracture toughness of the tested composite under high-rate loading is at least 50% higher compared to quasi-static loading.
COMPOSITES PART B-ENGINEERING
(2022)
Article
Engineering, Multidisciplinary
U. A. Khashaba
Summary: A new drilling approach using controllable force for clamping the specimen was implemented to investigate the influence of cutting and support conditions on thrust force, delaminations, and burr factor in drilling woven GFRP composites. A series of ASTM tests were conducted to determine mechanical properties and predict the critical thrust force for delamination initiation. Accurate measurement of delamination and burr areas was achieved using an inexpensive image processing technique.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Engineering, Manufacturing
F. Benazzo, D. Rigamonti, G. Sala, A. M. Grande
Summary: Self-healing and healable Fibre Reinforced Polymer composites (FRPs) have potential for reducing weight and increasing the lifetime of aerospace structures. However, there is no generally accepted method for evaluating their healing efficiency. This paper discusses different testing methods and their advantages and disadvantages when applied to healing FRPs, highlighting the inconsistencies found among investigations and providing tools for choosing the most adequate test method.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2023)
Article
Materials Science, Composites
Zhouyi Li, Zhen Wang, Weibang Lu, Xi Zhou, Tao Suo
Summary: This study investigated the loading rate sensitivity of mode II fracture behavior of composites toughened by carbon nanotubes (CNTs). It was found that under quasi-static loading conditions, increasing the number of CNT layers can improve the fracture toughness of the composites, while under dynamic loading conditions, the effect of increasing CNT layers on fracture toughness is minimal.
COMPOSITES SCIENCE AND TECHNOLOGY
(2021)
Article
Materials Science, Composites
Jagan Selvaraj, Luiz F. Kawashita, Mehdi Yasaee, Gordon Kalwak, Stephen R. Hallett
Summary: A novel cohesive element formulation is proposed for modelling composite delamination, offering increased stability and requiring fewer elements. This new formulation combines nodal rotations and multiple integration points to improve the accuracy of delamination propagation simulation.
COMPOSITES SCIENCE AND TECHNOLOGY
(2021)
Article
Mechanics
Edore G. Arhore, Mehdi Yasaee, Iman Dayyani
Summary: The study found that the geometry of the outer adherend directly affects the strength of adhesively bonded joint under tensile load, while it has little impact on joints subjected to bending load. Genetic algorithm and topology optimization methods show differences in optimizing the joint geometry, with the optimum joint produced by the topology optimization offering the highest strength overall.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2021)
Article
Physics, Applied
Mohammad Naghavi Zadeh, Farbod Alijani, Xianfeng Chen, Iman Dayyani, Mehdi Yasaee, Mohammad J. Mirzaali, Amir A. Zadpoor
Summary: Mechanical metamaterials are advanced engineering materials with tunable elastic properties and a strong influence of Poisson's ratio on damping performance. Geometrical design plays a crucial role in tuning the various types of quasi-static and dynamic properties of such materials.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Aerospace
Chao You, Mehdi Yasaee, Shun He, Daqing Yang, Yigeng Xu, Iman Dayyani, Hessam Ghasemnejad, Shijun Guo, Phil Webb, James Jennings, Giovanni Federico
Summary: This study presents a FEM-based preliminary structural sizing method for a single-aisle wing box structure. Various load cases representing typical aircraft manoeuvres, engine loads, landing and ground handling conditions are considered. The sensitivity analysis shows the importance of considering buckling and fatigue constraints, aircraft rolling loads, engine loads, and landing loads in sizing.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
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
Mechanics
Jagan Selvaraj, Luiz F. F. Kawashita, Stephen R. R. Hallett
Summary: A computationally efficient method for discrete modelling of cracks in laminated composite structures using explicit time integration is proposed. The method addresses the challenges of discrete crack modelling by employing mixed time integration or subcycling, and minimizing the impact on the surrounding stress field through nodal force balance.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
Amit Ramji, Yigeng Xu, Mehdi Yasaee, Marzio Grasso, Philip Webb
Summary: Experimental results show that using veil interleaving in CFRP laminates can reduce and shift damage location, impacting stiffness, with differences observed after the Delamination Threshold Load (DTL). This method also achieves a smoothing effect in impact force history and provides important insights into damage characteristics.
INTERNATIONAL JOURNAL OF IMPACT ENGINEERING
(2021)
Article
Mechanics
Bing Zhang, Giuliano Allegri, Stephen R. Hallett
Summary: This paper presents a novel numerical technique for modelling fatigue delamination growth in fibre reinforced composites. The simulation approach can describe fatigue delamination under various loading conditions. The method combines twin cohesive zone models with an artificial neural network. The application of this technique has been successfully demonstrated through verification and validation.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2022)
Article
Engineering, Manufacturing
A. D. Cochrane, J. Serra, J. K. Lander, H. Boehm, T. Wollmann, A. Hornig, M. Gude, I. K. Partridge, S. R. Hallett
Summary: Significant research has been conducted on the small-scale failure behavior of Z-pinned composite laminates, but little work has been done on the large-scale, high strain-rate behavior of Z-pinned composites at the structural level. Small-scale testing is not sufficient to fully study the crack bridging effects of Z-pins, while full-scale testing on real components is difficult due to complex geometries and failure mechanisms. A novel cantilever soft body impact test has been developed to study the behavior of Z-pin arrays under high strain-rate conditions.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2022)
Article
Engineering, Manufacturing
Vahid Zal, Mehdi Yasaee
Summary: This work presents a new method of analyzing the vertical alignment of short fibers inside transparent resin layers using in situ measuring of light transmission. The method involves placing a light source on one side of the composite layer and measuring the transmitted light intensity on the opposite side. The study evaluated the alignment of short nickel coated carbon fibers inside epoxy resin layers under a magnetic field, considering factors such as fiber content, field strength, fiber length, and resin thickness. The research found that the ratio of fiber length and resin thickness sets a limit to the alignment degree. Additionally, an analytical model was introduced to predict average fiber angles based on sample configuration, which showed good agreement with experimental results.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2022)
Article
Materials Science, Composites
Tianqi Zhang, Mehdi Yasaee
Summary: This paper explores the effect of thermoplastic interleaves on the mechanical performance of open-hole notched CFRP composites and examines the effectiveness of healing treatment on the thermoplastic interleaves post drill operation. Both experimental and numerical analysis results show that thermoplastic interleaves can enhance interfacial fracture toughness and reduce stress concentrations, resulting in higher overall load carrying capacity.
COMPOSITES SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Manufacturing
Tharan Gordon, Xiaodong Xu, Michael R. Wisnom, Stephen R. Hallett, Byung Chul Kim
Summary: This paper presents an experimental investigation into the effect of scarfed ply drops on the low velocity impact response of carbon/epoxy laminates. It was found that the scarfed ply drops reduced stress concentrations and prevented fibre breakage. Furthermore, laminates with scarfed ply drops exhibited less delamination and internal matrix cracking, indicating higher damage resistance compared to laminates with conventional ply drops.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2023)
Article
Mechanics
Kilian Gruebler, Daniel Thomson, Nik Petrinic, Michael R. Wisnom, Stephen R. Hallett
Summary: A study was conducted to examine the impact of multi-axial stress states and reinforcement type on the constitutive response of fibre reinforced epoxy polymers using both experimental and numerical methods. The study investigated the constitutive behavior of carbon and glass fibre reinforced epoxy resin under different stress states. The experiments were simulated using an enhanced non-linear material model that accurately represented the elastic and plastic behavior. The results demonstrated that the fiber reinforcement type and multi-axial stress state significantly influenced the overall constitutive response.
COMPOSITE STRUCTURES
(2023)
Article
Materials Science, Composites
Pok Lam Marvin Lau, Jonathan P-H Belnoue, Stephen R. Hallett
Summary: This paper presents a novel methodology that can automatically detect and isolate individual ply information within a low-resolution composite laminate image. The method can quickly process the image and create accurate geometric models with minimal user interaction. The generated finite element models can be used for structural and strength simulations to analyze the impact of waviness defects.
COMPOSITES AND ADVANCED MATERIALS
(2023)
Article
Materials Science, Composites
Ioannis K. Giannopoulos, Mehdi Yasaee, Nikolaos Maropakis
Summary: The study compared the experimental impact tests with numerical simulations of steel ball impact onto carbon composite laminate, showing good agreement overall. The higher fidelity model captured more detailed damage of the laminate, but with 80% higher computational cost than the lower fidelity model.
JOURNAL OF COMPOSITES SCIENCE
(2021)
