Review
Mechanics
Jisiyuan Cheng, Yingjie Xu, Weihong Zhang, Weiwei Liu
Summary: This paper reviews published multi-scale research into polymer composite laminates reinforced by z-pins. Micro-scale models are used to characterize the micro mechanisms and microstructure of z-pin bridging, while macro-scale models analyze the effects of z-pinning on the mechanical performances of composite laminates. The finite element models show good agreement with experimental phenomena and analytical conclusions.
COMPOSITE STRUCTURES
(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
Mechanics
Weiwei Wang, Han Wang, Shaohua Fei, Huiyue Dong, Yinglin Ke
Summary: This paper proposes a new concurrent multiscale unit cell model to investigate the in-plane micro-damage evolution of Z-pinned composite laminates (ZCL). The research indicates that in-plane micro-damage initiates from the interface between Z-pin and matrix, with stress concentration and higher local fiber volume fraction playing a major role.
COMPOSITE STRUCTURES
(2022)
Article
Engineering, Mechanical
Binbin Liao, Jianwu Zhou, Shigang Ai, Yuan Lin, Li Xi, Yong Cao, Dengbao Xiao
Summary: The study investigates the impact of laminate thickness on the low velocity impact responses of Z-pinned laminates, demonstrating that Z-pins are effective in preventing delamination, especially when impact energy exceeds a certain threshold. As laminate thickness increases, the delamination suppression is less effective for thin laminates compared to intermediate-thickness laminates, while thick laminates may experience weaker suppression effectiveness due to smaller bridging forces and slight Z-pin pull-out at the same impact energy.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Engineering, Manufacturing
Binbin Liao, Jianwu Zhou, Jinyang Zheng, Ran Tao, Li Xi, Tian Zhao, Ying Li, Daining Fang
Summary: This study investigated the impact of Z-pins on the low velocity impact performance of composite laminates. It was found that although Z-pins could not delay delamination initiation, they were able to enhance resistance to penetration, with 0 degrees Z-pinning showing better effectiveness in suppressing delamination damage and internal defects.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2021)
Article
Engineering, Manufacturing
L. Francesconi, F. Aymerich
Summary: This paper reports on an experimental investigation into the compression after impact (CAI) performance of thin z-pinned carbon-epoxy laminates. The damage induced by impact and the damage mechanisms leading to CAI failure were characterized. The study shows that the effect of z-pins on the post-impact strength of the laminates depends on the energy of the impact.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2022)
Article
Materials Science, Composites
Xiaoxu Wang, Wen Chen, Youhong Tang
Summary: Z-pin pull-out tests were conducted to investigate the meso interface structure and debonding position of the z-pin/laminate system. The results revealed that the interface consisted of two meso interface components, with debonding occurring at the weaker one. The z-pin with better molding quality exhibited higher interfacial bond shear stress and debonding primarily occurred at Interface I, while the z-pin with poorer molding quality had lower interfacial bond shear stress and debonding mainly occurred at Interface II. However, this type of z-pin showed higher resistance at the final frictional pull-out stage.
COMPOSITES COMMUNICATIONS
(2022)
Article
Mechanics
Shengnan Zhang, Yingjie Xu, Weihong Zhang, Xinyu Hui
Summary: A novel micro-mechanical modeling approach was developed to predict the partially debonding of Z-pin reinforced composite laminates after the cure process. Numerical simulation results showed that residual stress concentration mainly occurred in the interphase, potentially resulting in interfacial cracking around the Z-pin.
COMPOSITE STRUCTURES
(2022)
Article
Materials Science, Composites
Andre Knopp, Gerhard Scharr
Summary: This study demonstrates that notching of z-pins significantly increases the compression strength of laminates, with different notch designs impacting the results but not affecting the Young's modulus.
COMPOSITES SCIENCE AND TECHNOLOGY
(2021)
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
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
Materials Science, Composites
Shaohua Fei, Weiwei Wang, Han Wang, Di Yang, Huiming Ding, Haijin Wang, Jiangxiong Li, Yinglin Ke
Summary: This study introduces an ultrasound guided Z-pinning process to enhance the interlaminar performance of composite laminates. Experimental results demonstrate that the use of fine Z-pins can significantly improve the mechanical properties of composites.
COMPOSITES SCIENCE AND TECHNOLOGY
(2021)
Article
Mechanics
Binbin Liao, Zhongwei Zhang, Liping Sun, Jianwu Zhou, Panding Wang, Yuan Lin, Wenwang Wu, Daining Fang
Summary: This study investigated the impact of Z-pinning technique on composite laminate under low velocity impact. The results showed that at high impact energy, Z-pinning could effectively suppress delamination damage and internal defects, reducing damage interference.
COMPOSITE STRUCTURES
(2021)
Article
Materials Science, Composites
Bowen Gong, Huan Wang, Martinson Nartey, Wenting Ouyang, Jing Ye, Shaoxing Qu, Hua-Xin Peng
Summary: An experimental investigation was conducted on unpinned and Z-pinned quasi-isotropic carbon fibre/epoxy laminates to understand the damage evolution and failure mechanisms under fatigue loading. The Z-pinned laminates exhibited poor fatigue behavior at low cycles but had higher stiffness. The failure modes evolved from delamination to on-axial fiber failure.
COMPOSITES SCIENCE AND TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Asif Khan, Heung Soo Kim
Summary: A supervised machine learning framework was proposed for local assessments of delamination and transducer debonding in smart composite laminates using their low-frequency structural vibrations. Load independent discriminative features were identified and linear discriminant analysis outperformed other classifiers. The issue of overfitting was addressed by evaluating the classifier's predictive performance on independent test cases, providing insightful guidelines for the assessment of multidamages in smart composite laminates.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2022)
Article
Materials Science, Composites
Andre Knopp, Gerhard Scharr
JOURNAL OF COMPOSITE MATERIALS
(2017)
Article
Materials Science, Multidisciplinary
Andre Knopp, Christian Duesterhoeft, Martin Reichel, Gerhard Scharr
JOURNAL OF MATERIALS SCIENCE
(2014)
Article
Mechanics
Andre Knopp, Gerhard Scharr
COMPOSITE STRUCTURES
(2020)
Article
Materials Science, Composites
Andre Knopp, Gerhard Scharr
Summary: This study demonstrates that notching of z-pins significantly increases the compression strength of laminates, with different notch designs impacting the results but not affecting the Young's modulus.
COMPOSITES SCIENCE AND TECHNOLOGY
(2021)
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
Materials Science, Composites
Andre Knopp, Gerhard Scharr
JOURNAL OF COMPOSITES SCIENCE
(2020)
Article
Materials Science, Composites
Andre Knopp, Gerhard Scharr
JOURNAL OF COMPOSITES SCIENCE
(2020)
