Quasi-static Perforation Tests Research Articles

Comparative study of quasi-static indentation (QSI) response of composites used in maritime transport

The objective of this experimental investigation is to study the behavior of quasi-static indentation (QSI) of two composite panels (sandwich composite with PVC core -GFRP laminated composite) used in maritime transport, in order to develop a basic understanding of their behavior under the dynamic loading of low-velocity impact. To do so, a series of low-velocity quasi-static perforation tests were performed until the entire penetration, the force–displacement curves, the absorbed energy, and the resultant damage under this quasi-static loading were compared and analysed. The experimental results show that the absorbed penetration energy and the induced damage of the 8 mm laminates for the sandwich composites are almost the same. It was found that the effect of PVC core on quasi-static indentation behavior for sandwich composite is almost negligible, due to its low penetration resistance.

Investigation of metal-matrix composite based hybrid laminates under quasi-static penetration and Charpy impact loading

The primary objective of the research presented here is to investigate the mechanical properties of SiCp/AA6061 based, directly-bonded hybrid laminates (HLs). Hot-pressing technique is introduced to manufacture polymer/metal/polymer HLs. Two types of thermoplastic composites (TPCs) are stacked with the metal-matrix composite (MMC). Long glass fiber-reinforced polypropylene (PP) composite sheets (20 wt% and 40 wt%) are placed in the front of and rear of the MMC plates. In this way, the effect of PP composites with different fiber amounts on perforation and Charpy impact behavior is evaluated. Failure mechanisms of the HLs are also scrutinized. The experimental results show that the HLs result in improved mechanical properties. Enhancement of the maximum penetration force is more pronounced in the HLs struck from the TPC-40. The absorbed energy in the quasi-static perforation tests is found to be up to 12.24 and 23.59 times higher compared to monolithic TPC-20 and TPC-40, respectively. The images of the damaged HLs demonstrate the plugging shear out and fiber pullout at the strike and rear faces, respectively. The MMC-based HLs also lead to the increase in the impact resistance. By replacing the blow surface from TPC-20 to TPC-40, the flatwise Charpy impact strength significantly improves from 122 kJ/m 2 to 137.11 kJ/m 2 . The scanning electron microscopy (SEM) investigations after the impact experiments support that the fiber fracture is the dominant mechanism for failure mode of the faces under impact. Besides, signs of ductile fracture are seen for the MMC layer.

Identification of Armox 500T steel failure properties in the modeling of perforation problems

The paper presents a description of fracture surface development for Armox 500T steel in the space of triaxiality and the Lode parameter. The aim of this work was achieved with the application of the proposed coupled experimental-numerical procedure. Firstly, an appropriate set of basic tests was proposed and performed with experimental data acquisition, and then simulated numerically in equivalent conditions. Subsequently, the combination of experimental and numerical results allowed the fracture surface of Armox 500T to be built with the biharmonic spline interpolation method. The obtained initial fracture surface was calibrated in an iterative procedure based on the results of quasi-static perforation tests with pointed, flat and hemispherical punches. Finally, the predictive capability of the developed fracture surface was confronted with other failure models disclosed in the literature for Armox 500T. The proposed failure model provided a response that was found to be qualitatively and quantitatively superior to the other models because it accurately reflected the experimentally observed perforation patterns and force histories. On the basis of the character of the designed surface, it can be stated that Armox 500T armor steel demonstrates high sensitivity of fracture properties to both triaxiality and the Lode parameter.

The effect of silica/polyurethane waterborne dispersion on the perforating features of impregnated polypropylene-based fabric

In an attempt to improve the puncturing behavior of a commercial technical textile, this study investigated the effects of fabric impregnation with waterborne polyurethane dispersions (WPUDs). The infusing solutions were prepared by mixing a commercially available WPUD with other components, such as water, hydrophilic and hydrophobic silica (SiO2) nanoparticles, and a crosslinker. Quasi-static perforation tests were performed on a dynamometer machine equipped with a spherical spike and pointed blade as piercing probes. The results showed that the polyurethane impregnation augmented the puncture performances of the treated textiles. Then, further improvements in the spike and blade strength of the impregnated fabrics were obtained by adding hydrophilic silica nanoparticles and crosslinker into WPUDs, respectively. No effect of silica functionalization (hydrophilic or hydrophobic) has been verified on the mechanical features of the respective treated samples for the tested filler contents of 3% and 5% in wt. The best fabric features (blade strength increase of +63% and puncture strength increase of +71% compared to the neat material) were obtained by combining the two additives, nano SiO2 and crosslinker, into the polyurethane. The performances of these last systems were also superior to those obtained by doubling the amount of polymeric dispersion applied to the neat materials. The discussion of the results was supported by electron scanning microscopy, infrared spectroscopy, and further measurements of the cutting resistance. Finally, the mass per unit area of the substrate for the impregnated samples was measured in order to assess weight gain due to treatment.

Effect of thickness on the damage tolerance of glass/epoxy laminates subject to repeated impacts

To evaluate the influence of layer and laminate thickness on the repeated impact response of E-glass/epoxy laminates, two types of cross-ply stacking sequences ([0/90]3n and [03/903]n), with two different thicknesses (4 mm and 8 mm), were analyzed. The investigation, led by running quasi-static perforation tests and repeated impact tests, outlined the better performance of [03/903]n laminates. Experimental results were analyzed through a macroscopic damage variable (damage index DI) and by microscopic observation and digitalized profiles of impacted specimens. The higher damage tolerance of [03/903]n laminates was found to depend on the capability of spreading the damage over a more extended area and of tolerating a higher permanent deflection. For both laminate types, the end of the steady damage accumulation phase was observed to correspond to through-thickness transverse cracking.

Ballistic impact behaviors of aluminum alloy sandwich panels with honeycomb cores: An experimental study

To study the protection property of aluminum alloy sandwich panels with honeycomb cores under the attack of bullets or debris, quasi-static perforation, and ballistic impact tests were conducted, in which the thicknesses of the face sheet and core were 0.5–2.0 and 12.7 mm, respectively, while projectiles with diameter 7.5 mm and impact velocity 50–220 m/s were employed. Based on the experiments, the influences of impact velocity, face sheet thickness, core density as well as the nose shape of the projectiles were investigated. The results showed that in the impact tests, the sandwich panels dissipated much more energy than those in quasi-static perforation tests, and the energy absorption and ballistic limit of the sandwich panels increased with the increase of impact velocity. The influence of face sheet thickness was more remarkable than the core density, which was due to the relative density of honeycomb is too small. Although the increase of core density could induce the increase of energy absorption, this effect is more effective for thinner face sheet. Moreover, under the same impact velocity about 200 m/s and face sheet thickness 1.0 mm, the ballistic limit for conical-nosed projectile is highest, while it is lowest for flat-nosed projectile.

An investigation on the energy absorption of aluminum foam core sandwich panel via quasi-static perforation test

Aluminum foams are a novel branch of advanced materials with superior properties. Sandwich structures with aluminum foam core are good energy absorbers. In this paper, mechanical properties and energy absorption of aluminum foam sandwich panels subjected to quasi-static perforation tests with conical-nosed indenter were investigated experimentally. For this purpose sandwich panels consisting of two aluminum face-sheets and a closed cell aluminum foam core were fabricated. Quasi-static perforation tests on fully fixed sandwich panels were carried out by a universal testing machine at a cross head speed of 0.02 mm/s. Force-displacement curves were recorded and peak piercing force and absorbed energy of sandwich panels were calculated accordingly. Effects of foam core density (0.5, 0.6 and 0.7 g/cm3) and thickness of face-sheets (0.6, 1 and 2 mm) and foam core (10, 20 and 30 mm) on the mechanical properties and energy absorption of samples were discussed. The results showed that increasing foam core and face-sheet thickness and foam core density led to more total absorbed energy being achieved and higher piercing force.

정적압입 관통 실험을 이용한 복합재 적층판의 고속충격 탄도한계속도 예측

The ballistic limit of Carbon/Epoxy composite laminates with the finite effective area are predicted by using the quasi-static perforation test and semi-empirical formula. The perforation energy were calculated from force-displacement curve in quasi-static perforation test. Also, the actual ballistic limit and penetration energy were obtained through the high-velocity impact test. The quasi-static perforation test and high-velocity impact test were conducted for the specimens with 3 different effective areas. In the high-velocity impact test, the air gun impact tester were used, and the ballistic and residual velocity was measured. The required inputs for the semi-empirical formula were determined by the quasi-static perforation tests and high-velocity impact tests. The comparison between semi-empirical formula and high-velocity impact test results were conducted and examined. The ballistic limits predicted by semi-empirical formula were agreed well with high-velocity impact test results.

Effect of Nanoclay on Quasi Static Perforation of Thin-walled Polymer Composite Laminates

In this study, the penetration and perforation performance of nanoclay reinforced unsaturated polyester resin/fibreglass nanocomposite laminates have been investigated via quasi-static indentation tests using ahemispherical nose indenter. Unsaturated polyester resin (UP) was mixed with 1.5 and 3 wt.% nanoclay using a homogenizer stirrer to prepare a homogeneous mix. UP reinforced nanocomposite was then utilized to manufacture 150 × 150 mm2 laminated composite panels using 400 g/m2 glass fibre woven roving via a hand lay-up process. X-ray diffractometry, transmission electron microscopy analysis, energy-dispersive X-ray (EDXA) analysis and measurement of viscosity changes in the liquid state resin confirmed the exfoliation and the intercalation of the nanoclay by the unsaturated polyester resin system used. Quasi-static perforation tests were conducted using a surface-hardened steel indenter with a hemispherical tip at 5 and 500 mm/min load rates on nanocomposite laminated plates. Measurement of the quasi-static force as a function of indenter displacement for all the specimens showed four distinct regions, namely penetration, perforation, exit and residual frictional force. The results indicated a clear role being played by the nanoclay filler as a secondary reinforcement, in terms of higher energy absorption in all four regions.

Study on impact perforation fracture mechanism in PMMA

Many studies on the hypervelocity impact problem in metallic materials have been conducted [1±3]. In these studies, rail guns, powder guns and light gas guns are used to launch projectiles. The correlation of target fracture morphology, absorbed energy, the penetration depth, and the crater diameter=volume with impact velocity is investigated. In the present study, polymeric materials are used as target material. The objective of the present study is to examine the fracture mechanism of polymeric materials by high velocity impact tests and quasistatic perforation tests. A target material is polymethylmethacrylate (PMMA). The target plate sizes are 115 mm3 115 mm and 214 mm 3 214 mm. Thickness of target specimens, t, are 1, 3, 5 and 10 mm. The target specimens are ®xed between two plates with circular holes. The diameters of the holes, D, are 100 mm and 200 mm. The high velocity impact tests and quasi-static perforation tests are impact test and perforation test into a ®xed circular plate. In high velocity impact tests, the experimental apparatus is composed of an air compressor and an air gun. Stainless and PMMA spherical projectiles, whose diameter is ,11 mm are launched by impact testing machine at various velocities up to 200 m sy1. In quasi-static perforation tests, the target specimen is perforated by a steel bar having a spherical head whose diameter is 10 mm. The tests are performed by using a universal testing machine. The cross head speeds are 0.5, 5.0 and 50.0 mm miny1. In high velocity impact tests, four typical fracture forms of targets and PMMA projectiles, respectively, were veri®ed. Fracture forms of targets are de®ned as ricochets, cracks, breaks and perforates. Those for projectiles are de®ned as intact, cracked, broken and shattered. Fig. 1 shows a ballistic phase diagram which indicates the relationships between the impact velocity and the fracture morphology of targets and projectiles. Fig. 2 shows the relation between impact velocity and perforated hole area. It is found that the hole area becomes similar to the maximum section area of the projectile at impact velocities above a certain value. For impact velocities below 100 m sy1, the perforation fracture is dominated by bending deformation. For impact velocities above 100 m sy1, bending deformation is very small before the projectile perforates the target. Fig. 3 shows typical load±displacement curves obtained by quasi-static perforation tests (D ˆ 100 mm, t ˆ 1 mm). It is seen that in this range of

高分子材料の衝撃貫通破壊について

High velocity impact tests are conducted by launching spherical stainless steel and PMMA projectiles into thin PMMA plate targets at various velocities. Ballistic phase diagrams are obtained which indicate the fracture behavior in targets and projectiles. Quasi-static perforation tests are also performed. The fracture surfaces in targets are examined microscopically.