Background
Composite material is being used in vehicles for protective structures against blast loading. Limited data is available which compare experimental works and numerical analysis in the open field environment. More data is needed in this area in order to be able to predict and use composite materials safely.
Methods
In this work, the response of woven glass/epoxy composite plates under blast loading was investigated, both experimentally and numerically. The plate was manufactured using glass/epoxy woven Cytec 120 °C curing system. The explosive material was Tri-Nitro-Toluen (TNT) with different masses, which are 60, 80, and 100 g. The stand-off distance was also varied, ranging from 300 up to 1000 mm. In the experimental work, a sewing needle pin was put under the plate to record the maximum deformation of the plate during TNT explosion. In the numerical analysis, LS-DYNA was used extensively. The composite plate was modeled as shell elements using MAT54, and the failure criteria was Chang-Chang failure criteria. The explosive TNT material was modeled in two different ways. First, it was modeled using CONWEP and the second was modeled using Smooth Particle Hydrodynamics (SPH). The numerical analysis results were then compared with the experimental data for the case of maximum deformation.
Results
Experimentally, the sewing needle method was able to measure the plate maximum deformation during the explosion. The numerical analysis showed that the SPH model gave better agreement with experimental results compared with CONWEP method. The SPH results were in the range of 8–18% compared to experimental data, while the CONWEP results were in the range of 14–43%.
Conclusion
Albeit its simplicity, sewing needle method was able to measure the maximum deformation for blast loading experimentation. The SPH model was better compared with CONWEP method in analyzing the response of composite plate subjected to blast loading.
This paper presents the development process of a laboratory-scale Lamb wave-based structural health monitoring (SHM) system for laminated composite plates. Piezoelectric patches are used in pairs as actuator/sensor to evaluate the time of flight (TOF), i.e. the time difference between the transmitted/received signals of a damaged plate and those of a healthy plate. The damage detection scheme is enabled by means of evaluating the TOF from at least three actuator/receiver pairs. In this work, experiments were performed on two GFRP plates, one healthy and the other one with artificial delamination. Nine piezoelectric transducers were mounted on each plate and the detection of the delamination location was demonstrated, using 4 pairs and 20 pairs of actuators/sensors. The combinations of fewer and more actuators/sensor pairs both provided a damage location that was in good agreement with the artificial damage location. The developed SHM system using simple and affordable equipment is suitable for supporting fundamental studies on damage detection, such as the development of an algorithm for location detection using the optimum number of actuator/sensor pairs.
Composite material is gaining acceptance for protective structures against explosion, such as granade explosion. This is due to its ligh tness and high strength. In this paper, the response of composite plate subjected to granade explosion was studied experimentally. The composite plate was made of glass and carbon fiber with different number of plies and lay-up. The plate dimension wa 250x250 mm. The granade contains 40 grams of TNT and the shell was made of cast iron. The total mass of the granade was 365 grams. The stand-of-distance was veried, which was 300, 500 and 1000 mm. The results showed that all specimens were able to keep their integrity without collapse. The carbon fiber composites showed some small fragmet penetration, while the glass fiber composites showed no fragment penetration although some delaminations occured. The almunium plate showed fragment penetration and large plastic deformation. Therefore in this case, composite plates performed better than the aluminium plates.
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