Damage is a key problem that limits the application of polymer membranes. In this paper, conductive carbon black (CB) and silicon dioxide (SiO₂)-reinforced polyvinylidene fluoride (PVDF) composites were prepared using a solution mixing method. Through a uniaxial tensile test, the fracture and damage characteristics of the material were analyzed. When the structure had inevitable notch damage, changing the notch angle was very helpful for the material to bear more load. In addition, when there were two kinds of fillers in the PVDF matrix at the same time, there was an interaction between particles. The microstructure of the composite was characterized by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and thermogravimetric (TG) analysis. The experimental results indicate that, when the ratio of CB:SiO₂:PVDF was 1:4:95, the general mechanical properties of the composite were the best.

The effects of shape memory alloy (SMA) wires on the damage behavior of glass fibers/epoxy resin composite laminates for the case of low-velocity impact are investigated experimentally and numerically. In this work, the low-velocity impact tests of SMAs/glass fibers/epoxy resin composite laminates are carried out. The elastic–plastic theory was adopted to simulate the mechanical behavior of SMA during the loading stage. The three-dimensional (3D) Hashin failure criterion is adopted in Abaqus/Explicit to model the damage initiation of composite laminates. The cohesive damage model is introduced to control the interface element and model the delamination failure. Moreover, the impact damage mechanisms of composite laminates are analyzed based on the experimental and numerical simulation results. These results show that the numerical results obtained in the present study have a reasonably good agreement with the experimental results. In addition, it is also found that impact damages are mainly caused by matrix cracks and delamination with no perforation for the case of 32-J impact energy, and impact damages are mainly caused by fibers breakage with perforation for the case of 64-J impact energy.

Glass fiber reinforced polymer (GFRP) due to its corrosion resistance is gaining popularity in the civil engineering community, as an alternative material to steel reinforcement. GFRP reinforced bar (rebar) has a high tensile strength with moderate elastic modulus and is elastic up to failure. However, it should not be treated in the same way as steel rebar because the interfacial bond behavior of GFRP bars to concrete is expected to vary from that of conventional steel bars, since various parameters that influence bond performance are different. This paper presents the results of an experimental and analytical studies on the bond strength of glass fiber reinforced polymer bars subjected to monotonic or reversed cyclic loads. The experimental program consisted of 30 test specimens. The test results indicated that the interfacial strength of the GFRP bars was quite different to that of the steel bars. In addition, the strength degradation of GFRP bars subjected to reversed cyclic load was more severe than that of the GFRP bars subjected to a monotonic load.

The low-velocity impact behavior of Shape Memory Alloy (SMA) reinforced resin matrix polymers is investigated and the influence of the SMA volume fraction on the impact performance of polymer composites is considered for the first time, which are the highlights in this paper. Firstly, 12 kinds of polymer composite specimens with different SMA volume fractions are fabricated in terms of the SMA layup spacing, SMA diameter, and the interaction between the two. Secondly, a low-velocity impact test is carried out in order to study the impact performances of the above polymer composites. Finally, the damage morphology of the specimen after impact is observed by the visualization method and the low-velocity impact performance of the 12 kinds of polymer composites is analyzed on the basis of the force and energy history curve.

In this paper, a progressive damage model reflecting the interaction between delamination and intralaminar crack is developed to predict fracture behaviors and the ultimate load-bearing ability of the fiber-reinforced polymer laminates subject to quasi-static load. Initiation and evolution of intralaminar crack in composites are modeled using a continuum damage mechanics model, which has the capability to reliably predict the discrete crack direction by introducing the crack direction parameter while analyzing the multi-failure of FRP composites. Delamination is modeled using a cohesive zone method with the mixed bilinear law. When the continuum damage model and cohesive zone model are used together, the interactive behavior between multiple failure mechanisms such as delamination induced by matrix cracking often seen in the failure of composite laminates is not generally captured. Interaction between delamination and intralaminar crack in FRP composite structures is investigated in detail and reflected in a finite element analysis in order to eliminate the drawbacks of using both models together. Good agreements between numerical results and experimental data are obtained.

In the present work, we study the low velocity impact, both central and eccentric, on square and rectangular laminated composite plates with embedded shape memory alloy (SMA) wires, which are stitched on the top and bottom surfaces of the plate, by using the finite element method. In finite element methods (FEM) simulations, a super-elastic SMA constitutive model is implemented in Abaqus/Explict by using a user defined material subroutine to describe the behaviors of SMAs. The three-dimensional (3D) Hashin failure criterion is adopted to model the damage initiation of laminated composite plates. To model the delamination failure, a cohesive damage zone model is introduced in interface elements. A comprehensive parametric study has been carried out to analyze the effects of eccentricity for the case of square and rectangular laminated composite plates.