Investigation of the effect of surface crack on low-velocity impact response in hybrid laminated composite plates

Composite materials have the characteristics of light weight, high strength, high modulus, and corrosion resistance. In this article, glass fiber/PVC curved sandwich structure composites with three curvature radiuses (80, 150, and 260 mm) and different sandwich structures were prepared by vacuum assisted resin transfer molding. The specimens were subjected to quasi-static indentation test and drop hammer impact test. The influence of curvature radius and ply sequence on the impact behavior of composites were analyzed by comparing the load displacement curve, pit depth, and energy loss. The compression after impact of specimens with different curvature radius and structure was carried out to explore the damage limit and toughness of composites. It is found that the maximum tensile properties of sandwich specimens are determined by the degree of resin infiltration into PVC foam panels. The impact performance is mainly attributed to the laying sequences of reinforcement. The instantaneous impact performance of free falling body is greatly affected by the curvature radius, and the post impact compression performance of sandwich composites is increased with increase of the curvature. The research could provide a theoretical basis for the application of combining curved surface and sandwich structure composites.

Section: Quasi-static Indentation Testmentioning

confidence: 60%

“…[ 19 ] Some fibers are pulled out, which absorbs more energy in the process of delamination and effectively hinders the propagation of crack. [ 20,21 ]…”

Section: Resultsmentioning

confidence: 99%

Study on impact behavior of glass fiber/PVC curved sandwich structure composites

Liu

Gao

2022

“…The magnitude of the fluctuation is linked to the type of damage. [ 46 ] Fluctuations with higher degrees are seen for the BCJs compared to the NCs filled BmCJs, showing the severity of the damage (Figure 3A). In the case of 3 J, the calculated displacements are 7.65E−4 and 6.15E−4 mm for the reference and multi‐scale nanocomposite samples, respectively.…”

Section: Resultsmentioning

confidence: 99%

Assessment of damage tolerance of bolted composite structures via “bearing‐after‐impact” tests

Kaybal

2022

Although bolted composite joints are mainly designed to resist bearing loading, dynamic loading such as low‐velocity impact can also be a severe threat because of its potential to reduce joint reliability. Surprisingly, it is still unclear how bolted composite joints perform after the dynamic loading, and its effect on the damage tolerance is unknown likewise. This study aims to evaluate experimentally the bearing‐after‐impact (BAI) damage tolerance of bolted glass‐fiber (GF) reinforced epoxy composite joints. For this, the GF/epoxy composite laminates were assembled in single‐lap shear joints firstly, and the bolted composite joints were subjected to low‐velocity impact tests at various energy levels from 3 to 10 J. Following that, standardized bearing tests were carried out to determine the damage tolerance of the laminated composites following the impact. Nanoclay fillers were also added to the epoxy matrix to improve damage tolerance. After the low‐velocity impact loading, the bearing strength diminishes by almost 22% for the bolted composite joints, while the reduction in damage tolerance is effectively limited with the nanoclay addition. However, as the impact energy increases, the efficiency of the nanofiller declines. Increased impact energy results in changes in failure modes, and nanofillers improve damage tolerance with additional nano‐scale toughness‐increasing mechanisms.

“…To characterize the LVI effect in composite structures in detail, force-displacement graphs were obtained by means of kinematic equations calculating that uses force-time data. [30,[52][53][54][55] From the force-time and forcedisplacement curves, the values characterizing the significant impact such as absorbed energy, impulse force, bending stiffness, maximum contact force, and maximum displacement are calculated for the impact energy between 2.5 and 25 J. These values obtained from the force histories in basalt/epoxy CPVs subjected to different impact energy under internal pressure are presented in Table 2 for GnPs unreinforced test specimens and in Table 3 for GnPs reinforced test specimens.…”

Section: Force-displacement Historiesmentioning

confidence: 99%

Experimental study on the effect of graphene nanoplatelets on the low‐velocity impact response of prestressed filament wound basalt‐based composite pressure vessels

Sepetcioglu

2021

The purpose of this study is to investigate the impact behavior of composite pressure vessel (CPV) in-service case. Additionally, graphene nanoplatelets (GnPs) were introduced to epoxy resin. [±55 ] 4 basalt/epoxy specimens were manufactured using the filament-winding method, and the low-velocity impact (LVI) response was investigated. The LVI tests of CPVs were performed at energy levels of 2.5, 5, 7.5, 10, 15, 20, and 25 J under 50 bar internal pressure. The prestress value considering the internal pressure used under service conditions was taken as 1:5 of the burst pressure of the basalt/epoxy CPVs. After the LVI tests, the contact force-time and force-displacement curves were acquired. Also, absorbed energy values by CPVs were calculated over the obtained curves. The effects of GnPs on damage formations on basalt/epoxy CPVs under LVI loads were evaluated based on microscopic analysis. According to evaluations, damage formations such as matrix cracks on outer and inner surfaces of CPV, transverse cracks, and delamination were detected. Test liquid was detected on the impact surface at 25 J LVI test. The leakage observed due to the 25 J impact energy proves that damages can result in a leakage path. Consequently, the areas of damage formed in the cross sections perpendicular to the axis of basalt/epoxy CPVs decrease with the addition of GnPs, and the CPVs are more resistant to LVI effects.