Investigation on impact behavior of FMLs under multiple impacts with the same total energy: Experimental characterization and numerical simulation

et al. 2021

Polymer Composites

An analytical model is presented to predict the progressive failure of reinforced thermoplastic pipes (RTPs) under axial compression, in which the existing homogenization method and a nonlinear stiffness degradation model are combined to predict the continuum damage mechanical response in an iterative and cyclic way. As the homogenization method ignores the effect of the cross‐sectional curvature on the damage sequence, a stress correction factor is defined to consider this effect. Once corrected stresses satisfy Hashin‐Yeh failure criteria, the nonlinear stiffness degradation model is adopted to update the constitutive relationship established by the homogenization method. The proposed model is capable of identifying the damage location and failure mode, analyzing damage accumulation and predicting the ultimate compression. Meanwhile, ABAQUS Explicit quasi‐static analyses calling a user‐defined subroutine were conducted to capture the progressive failure mechanisms in 3D composites and verify the proposed model. The proposed model was found to give accurate prediction on the elastic stiffness, first ply failure, the damaged stiffness, the ultimate compression, and stress distributions. Furthermore, the effects of fiber's winding angles and the thickness‐radius ratios have been discussed, which illustrate that tensile failure mode would appear even when RTPs are under axial compression.

Section: Analytical Failure Modelmentioning

confidence: 92%

“…The damage occurs once the failure factor is greater than one. [ 18,19 ] When damage appears, the failure factor should be used to build the nonlinear stiffness degradation model: [ 25‐27 ]

d_{i} = 1 - \frac{1}{R_{i}^{k}}, ((), R_{i} \geq 1, k \geq 1; i = italicft, italicfc, italicmt, italicmc, italicld) .

where, d i is the damage factor. k is a constant, which could reflect the nonlinearity of the degradation model when it is greater than 1.…”

Section: Analytical Failure Modelmentioning

confidence: 99%

An analytical model for the progressive failure prediction of reinforced thermoplastic pipes under axial compression

Liu

et al. 2021

Polymer Composites

“… Note : The subscripts f and m represent fiber and matrix; t and c denote tensile and compression. [ 38–41 ] …”

Section: Numerical Modelsmentioning

confidence: 99%

Mechanical response and critical failure mechanism characterization of notched carbon fiber reinforced polymer laminate subjected to tensile loading

et al. 2020

Polymer Composites

Self Cite

The purpose of this article is to investigate the mechanical responses and critical failure mechanisms of notched composite laminates with the aid of numerical and experimental approaches, considering the effect of notch geometry, notch size and off-axis angle. Quasi-static tensile tests are implemented to study the influence of design variables on the mechanical response, during which the relationship of force vs displacement and strain distributions are collected by means of digital image correlation technique. Subsequently, the numerical simulation is implemented in ABAQUS/Explicit through a progressive damage model integrated with a VUMAT subroutine. Meanwhile, the initiation and propagation of damage are explored through the damage morphologies, combining with the logarithmic strain components from numerical predictions. Results show that notch strength and failure strain are more closely associated with off-axis angle and notch size compared with notch geometry. In addition, with the increase of off-axis angle, the contribution of fiber is increasingly weakened, the damage mode gradually varies from fiber fracture to pull out accompanied with the damage near the notch changing from fiber fracture to delamination. Meanwhile, the critical failure mechanism varies from tension dominated to tension-shear/ shear dominated as the off-axis angle grows larger. K E Y W O R D S composite laminates, digital image correlation, failure mechanism, notch strength 1 | INTRODUCTION Carbon fiber reinforced polymer (CFRP) laminate has been increasingly applied in light of its outstanding performance and superior damage tolerance. Compared with traditional materials, it has many typical advantages, such as high specific strength and stiffness, [1-3] improved impact and fatigue resistance, [4-6] perfect corrosion resistance and moistureproof ability, [7] and so forth. During the application, in addition to the complicated loading conditions, the unavoidable notches for mechanical connections also pose a risk to the load-bearing capacity and service life. In addition, notch geometry and notch size are usually diversified to facilitate the connection of structural components, which significantly diminishes the mechanical properties and further complicates the exploration of mechanical behaviors. Furthermore, due to the anisotropy, brittleness, heterogeneity, and obvious difference between the interlaminar and intralaminar property, damage patterns, and failure mechanisms of composites also present complexity and diversity. [8]

“…Therefore, in order to enhance the bonding performance between aluminum sheet and composite laminates, it is necessary to conduct some treatments on the surface of aluminum sheets, which can be summarized briefly as the following: decontaminating, degreasing, deoxidizing, anodizing, cleaning and drying. 33 After these procedures, three aluminum layers and two composite laminates are bonded together with epoxy primer. Then large FML panels are cured at 135 C and 0.5 MPa in a vacuum tank for 2 h.…”

Section: Specimen Preparationmentioning

confidence: 99%

Tensile mechanical behavior and failure mechanisms of multihole fiber metal laminates—Experimental characterization and numerical prediction

Journal of Reinforced Plastics and Composites

et al. 2020

Self Cite

This work mainly investigates the effects of the hole number and layer direction on the tensile mechanical behavior and failure mechanisms of multihole fiber metal laminates by experimental and numerical methods. With the aid of digital image correlation technique, tensile tests are implemented to obtain mechanical responses of different multihole fiber metal laminates. Subsequently, numerical simulation considering thermal residual stress is conducted to elucidate the failure modes and progressive damage evolution of multihole fiber metal laminates, which integrates the progressive damage model of composite laminates and a cohesive zone model between aluminum sheet/composite laminates. Finally, numerical predictions are found in a good agreement with experimental measurements, in terms of mechanical responses and fracture morphologies. Results demonstrate that the number of holes has negligible influence on the ultimate tensile strength, whereas affects the final failure strain of multihole fiber metal laminates evidently. With the increase of layer direction, the fracture morphology changes from evident brittle fracture to fiber pull-out and matrix damage, which indicates that the critical failure mechanism of multihole fiber metal laminates changes from tension dominated to tension–shear dominated. Additionally, the longer loading history from initial damage to final failure of composite laminates demonstrates the significance of considering progressive damage behavior in numerical simulation.