The failure mechanism of carbon fiber-reinforced composites under longitudinal compression considering the interface

2017 ◽  
Vol 24 (3) ◽  
pp. 429-437 ◽  
Author(s):  
Geng Han ◽  
Zhidong Guan ◽  
Xing Li ◽  
Ruipeng Ji ◽  
Shanyi Du
Keyword(s):  
Failure Mechanism ◽  
Failure Mode ◽  
Cohesive Zone Model ◽  
Progressive Failure ◽  
Micromechanical Model ◽  
Kink Band ◽  
Zone Model ◽  
Longitudinal Compression ◽  
Fiber Failure ◽  
Damage Initiation

AbstractIn this paper, a longitudinal compression experiment of composites was conducted and the macroscopic failure mode was obtained. Also, the microscopic failure morphologies of longitudinal compression and kink band were observed by using scanning electron microscopy. It can be seen that, under compression, fibers bend and form a kink band, which is the most typical failure mode. Then a micromechanical model of fiber random distribution based on the random collision algorithm, which can reveal the progressive failure mechanism of longitudinal compression considering the kink-band deformation, was established, with two dominant damage mechanisms – plastic deformation and ductile damage initiation of the polymer matrix and interfacial debonding included in the simulation by the extended Drucker-Prager model and cohesive zone model, respectively. Through numerical simulation, the loading and failure procedures were divided into three stages: elastic domain, softening domain and fiber failure domain. It can be concluded that the kink band was a result of fiber instability (micro-bulking), which is caused by the elastic bending of fibers. The fibers rotate and break into two places, forming a kink band. Then the fibers rotate further until the matrix between the fibers fails and the kink-band breaks and, hence, the composite loses its load-bearing capability.

Numerical simulation of single-lap adhesive joint of composite laminates

2018 ◽  
Vol 37 (8) ◽  
pp. 520-532 ◽  
Author(s):  
Zhang Taotao ◽  
Luo Wenbo ◽  
Xiao Wei ◽  
Yan Ying
Keyword(s):  
Numerical Simulation ◽  
Cohesive Zone Model ◽  
Tensile Load ◽  
Zone Model ◽  
Composite Joints ◽  
Universal Method ◽  
Continuum Damage Mechanic ◽  
Damage Mechanic ◽  
Damage Initiation ◽  
Ultimate Failure

A universal method is established to research the various possible damage modes of adhesive bond of laminated composites with or without z-pin reinforcements under tensile loads through numerical simulation. A Continuum Damage Mechanic model based on Hashin damage criterion as a user-defined subroutine is developed to simulate the damage of laminates and Z-pins. The Cohesive Zone Model is used to simulate the damage of adhesive damage, interlayer delamination, and Z-pin slipping-out phenomenon. The numerical simulation method is validated for simulating the various damage modes of the usual composite joints through comparing the simulated results and experiments. The research shows that different ply sequences induce different damage modes and ultimate failure loads of composite joints. The ultimate failure load of joint under tension is not affected obviously whether the joints are reinforced with or without z-pins. The reason is that the damage initiation usually locates at the two sides of adhesive zone and z-pins do not react on the reinforcement under tensile load of joint.

Damage initiation and fracture analysis of honeycomb core single cantilever beam sandwich specimens

2020 ◽  
pp. 109963622090982 ◽  
Author(s):  
Vishnu Saseendran ◽  
Pirashandan Varatharaj ◽  
Shenal Perera ◽  
Waruna Seneviratne
Keyword(s):  
Cantilever Beam ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Element Model ◽  
Interface Fracture ◽  
Zone Model ◽  
Honeycomb Core ◽  
Damage Initiation ◽  
Foundation Model ◽  
Honeycomb Cell

Fracture testing and analysis of aerospace grade honeycomb core sandwich constructions using a single cantilever beam test methodology is presented here. Influence of various parameters such as facesheet thickness, core density, honeycomb cell-size, and core thickness were studied. A Winkler-based foundation model was used to calculate compliance and energy-release rate, and further compare with finite element model and experiments. A cohesive zone model was developed to predict the disbond initiation and simulate the interface crack propagation in the single cantilever beam sandwich specimen. The mode I interface fracture toughness obtained from the translating base single cantilever beam setup was provided as input in this cohesive zone model. It is shown that the presented cohesive zone approach is robust, and is able to capture the debonding phenomenon for majority of the honeycomb core specimens.

Thermo-Mechanical Analysis of Mixed-Mode Damage: Cohesive Zone Modeling

2015 ◽  
Author(s):  
Hussain Altammar ◽  
Sudhir Kaul ◽  
Anoop Dhingra
Keyword(s):  
Cohesive Zone ◽  
Composite Beam ◽  
Mixed Mode ◽  
Cohesive Zone Model ◽  
Mechanical Load ◽  
Element Model ◽  
Mechanical Analysis ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Damage Initiation

Damage detection and diagnostics is a key area of research in structural analysis. This paper presents results from the analysis of mixed-mode damage initiation in a composite beam under thermal and mechanical loads. A finite element model in conjunction with a cohesive zone model (CZM) is used in order to determine the location of joint separation as well as the contribution of each mode in damage (debonding) initiation. The composite beam is modeled by using two layers of aluminum that are bonded together through a layer of adhesive. Simulation results show that the model can successfully detect the location of damage under a thermo-mechanical load. The model can also be used to determine the severity of damage due to a thermal load, a mechanical load and a thermo-mechanical load. It is observed that integrating thermal analysis has a significant influence on the fracture energy.

scholarly journals Analysis on Failure Mechanism of Scarf Joints With Brittle-Ductile Adhesives Subjected to Uniaxial Tensile Loads

2013 ◽  
Author(s):  
Lijuan Liao ◽  
Toshiyuki Sawa ◽  
Chenguang Huang
Keyword(s):  
Failure Mechanism ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Adhesive Layer ◽  
Uniaxial Tensile ◽  
Zone Model ◽  
Displacement Curve ◽  
Failure Energy ◽  
Complete Failure ◽  
Scarf Joints

The failure mechanism of scarf joints with a series of angles and brittle-ductile adhesives subjected to uniaxial tensile loads is analyzed by using a numerical method which employs a cohesive zone model (CZM) with a bilinear shape in mixed-mode (mode I and II). The adopted methodology is validated via comparisons between the present simulated results and the existing experimental measurements, which illustrate that the load-bearing capacity increases as the scarf angle decreases. More important, it is observed that the failure of the joint is governed by not only the ultimate tensile loads, but also the applied tensile displacement until complete failure, which is related to the brittle-ductile properties of the adhesive layer. In addition, failure energy, which is defined by using the area of the load-displacement curve of the joint, is adopted to estimate the joint strength. Subsequently, the numerical results show that the strength of the joint adopting ductile adhesive with higher failure energy is higher than that of the joint using brittle adhesive with lower failure energy.

scholarly journals Study on Shear Mechanism of Bolted Jointed Rocks: Experiments and CZM-Based FEM Simulations

2019 ◽  
Vol 10 (1) ◽  
pp. 62 ◽  
Author(s):  
Shubo Zhang ◽  
Gang Wang ◽  
Yujing Jiang ◽  
Xianlong WU ◽  
Genxiao Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Failure Mechanism ◽  
Laboratory Experiments ◽  
Shear Failure ◽  
Cohesive Zone Model ◽  
Rock Fracture ◽  
High Strength ◽  
Simulation Method ◽  
Jointed Rock ◽  
Zone Model

Based on the underground jointed rock of the Huangdao water sealed oil depot in China, the shear failure mechanism of bolted jointed rock is studied through laboratory experiments and numerical simulation. Laboratory experiments are performed to explore the shear behavior of bolted jointed rock with different joint roughness. Our results show that using high strength bolts is beneficial to improving the shear strength of the jointed rock, but the high strength of bolts can also lead to the rock fracture, which should be avoided. For this particular project site, experimental results indicate that 15% elongation is the best. In addition, a new numerical simulation method with CZM (cohesive zone model) used for modeling the shearing process of bolted jointed rock is proposed. It can reasonably describe the characteristics of jointed rock as a discontinuous medium, and bolt as a continuous medium, that replicate well the shearing process. The numerical model is then verified by comparing the experiment results, and it can be effectively be applied to the simulation of joint shearing process. Finally, we use this simulation method to explore the shear failure mechanism of bolted joints, and find that the root cause of rock failure is the deformation mismatch between the bolt and the surrounding rock. The tensile stress between them eventually causes the rock to fracture near the bolt hole.

The effects of thermal residual stresses and interfacial properties on the transverse behaviors of fiber composites with different microstructures

2017 ◽  
Vol 24 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Xiaojun Zhu ◽  
Xuefeng Chen ◽  
Zhi Zhai ◽  
Zhibo Yang ◽  
Qiang Chen
Keyword(s):  
Residual Stresses ◽  
Cohesive Zone Model ◽  
Micromechanical Model ◽  
Interfacial Properties ◽  
Zone Model ◽  
Computational Accuracy ◽  
Fiber Model ◽  
Thermal Residual Stresses ◽  
Generalized Method Of Cells ◽  
Experimental Values

AbstractThis study presents a new micromechanical model to investigate the effects of thermal residual stresses and interfacial properties on the transverse behaviors of SiC/Ti composites with different microstructures. In this model, the fiber-matrix interface is modeled by the bilinear cohesive zone model. The interface model is introduced into the generalized method of cells, which has the advantage of computational accuracy and efficiency. At the same time, the generalized method of cells is extended to consider thermal residual stresses within the fiber and matrix phases. Thermal residual stresses are found to have a significant influence on the transverse behaviors of the composites. Compared with the perfect interface, the transverse behaviors of the composites with weak interface bonding are much lower. Moreover, with the increase of fiber fraction, the stiffness of the composites increases before debonding occurs while the saturation stress decreases. The predicted results using the circular fiber model and considering thermal residual stresses are more consistent with the experimental values compared with the results using the square or elliptical fiber model. When the stress concentration factor is considered and the interface is weakly bonding, the strength predictions are much better than the results using the perfect bonding.

scholarly journals Effect of Mesh Sensitivity and Cohesive Properties on Simulation of Typha Fiber/Epoxy Microbond Test

Computation ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 2
Author(s):  
Ikramullah ◽  
Andri Afrizal ◽  
Syifaul Huzni ◽  
Sulaiman Thalib ◽  
H. P. S. Abdul Khalil ◽  
...  
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Natural Fibers ◽  
Large Data ◽  
Zone Model ◽  
Damage Initiation ◽  
Fine Mesh ◽  
Cohesive Properties ◽  
Macro Scale ◽  
Microbond Test

The microbond test for natural fibers is difficult to conduct experimentally due to several challenges including controlling the gap distance of the blade, the meniscus shape, and the large data spread. In this study, a finite element simulation was performed to investigate the effects of the bonding characteristics in the interface between the fiber and matrix on the Typha fiber/epoxy microbond test. Our aim was to obtain the accurate mesh and cohesive properties via simulation of the Typha fiber/epoxy microbond test using the cohesive zone model technique. The axisymmetric model was generated to model the microbond test specimen with a cohesive layer between the fiber and matrix. The cohesive parameter and mesh type were varied to determine the appropriate cohesive properties and mesh type. The fine mesh with 61,016 elements and cohesive properties including stiffness coefficients Knn = 2700 N/mm3, Ktt = 2700 N/mm3, and Kss = 2700 N/mm3; fracture energy of 15.15 N/mm; and damage initiation tnn = 270 N/mm2, ttt = 270 N/mm2, and tss = 270 N/mm2 were the most suitable. The cohesive zone model can describe the debonding process in the simulation of the Typha fiber/epoxy microbond test. Therefore, the results of the Typha fiber/epoxy microbond simulation can be used in the simulation of Typha fiber reinforced composites at the macro-scale.

The Research of the Effective Moduli of Particle Reinforced Polymer Composites Based on Interface Debonding

2009 ◽  
Vol 413-414 ◽  
pp. 211-217
Author(s):  
Xin Long Chang ◽  
Bin Jian ◽  
Chang Ouyang
Keyword(s):  
Polymer Composites ◽  
Cohesive Zone Model ◽  
Volume Fraction ◽  
Micromechanical Model ◽  
Interface Debonding ◽  
Zone Model ◽  
Effective Moduli ◽  
Reinforced Polymer ◽  
The Matrix ◽  
Particulate Size

This paper is devoted to studying influences of matrix/particle interface debonding and particulate size in micromechanical predictions of the effective moduli of particulate reinforced polymer composites (PRPC). The PRPC is regarded as a three-phase composite that includes the matrix, particle and interphase. The formulation for the effective moduli of the interphase is derived by the cohesive zone model, and combined with the Mori-Tanaka method, the micromechanical model for the effective moduli of the PRPC is formulated with emphasis on the effects of the matrix/particle interface, particulate size and volume fraction. The numerical example shows that the interface debonding, the particulate size and volume fraction have significant influences on the effective moduli of PRPC. The effective moduli of the PRPC can be used to characterize its damage degree.

scholarly journals Experimental-Numerical Failure Analysis of Thin-Walled Composite Columns Using Advanced Damage Models

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1506
Author(s):  
Patryk Rozylo ◽  
Katarzyna Falkowicz ◽  
Pawel Wysmulski ◽  
Hubert Debski ◽  
Jakub Pasnik ◽  
...  
Keyword(s):  
Experimental Study ◽  
Failure Analysis ◽  
Computational Models ◽  
Cohesive Zone Model ◽  
Progressive Failure ◽  
Experimental Tests ◽  
Zone Model ◽  
Channel Section ◽  
Composite Columns ◽  
Thin Walled

The paper analyzes the stability and failure phenomenon of compressed thin-walled composite columns. Thin-walled columns (top-hat and channel section columns) were made of carbon fiber reinforced polymer (CFRP) composite material (using the autoclave technique). An experimental study on actual structures and numerical calculations on computational models using the finite element method was performed. During the experimental study, post-critical equilibrium paths were registered with acoustic emission signals, in order to register the damage phenomenon. Simultaneously to the experimental tests, numerical simulations were performed using progressive failure analysis (PFA) and cohesive zone model (CZM). A measurable effect of the conducted experimental-numerical research was the analysis of the failure phenomenon, both for the top-hat and channel section columns (including delamination phenomenon). The main objective of this study was to be able to evaluate the delamination phenomenon, with further analysis of this phenomenon. The results of the numerical tests showed a compatibility with experimental tests.

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