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1

Energy balance modelling of high velocity impact effect on composite plate structures

Al-Waily M., Jaafar A.M.

Archives of Materials Science and Engineering

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2021

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Vol. 111, nr 1

14--33

EN

Purpose: In many military applications, composite materials have been used because of their high velocity impact resistance that helps absorption and dispersion energy. It is therefore used in armour and vehicles, aircraft and spacecraft that are subjected to impact of various shapes and velocities. Design/methodology/approach: In the theoretical part, the absorption energy equation for the sample was established by constructing an energy balance equation consisting of five types of energies, it is the compressive energy in the first region (the impact region), the tensile energy in the first region, the tensile energy in the second region, the energy of the shear plugging and the friction energy. Findings: It was found in the experiments that the tensile stress value increased by increasing the volume fraction of fibres to the polyester, and the value of compressive stress decreased. Also manufactured different types of impact samples with dimensions (20*20 cm2 ) and deferent thickness. The results were an increase in the amount of energy absorbed by increasing the ratio of the fibre to the polyester. It is found that the greatest effect in the equation of energy balance is the shear plugging energy, in which the value of the energy absorbed reached 38% of the total energy. And in the second degree friction energy, in which the value of the energy absorbed reached 27% of the total energy. while the other energies are relatively small but with important values, except for the tensile energy in the second region, the Kevlar-Polyester (40-60)%, so that the increase was more than four times the previous case. Research limitations/implications: Three types of reinforcing fibres were used: Kevlar, Carbon and Glass fibres with a matrix material as polyester. Six samples are made for tensile and compression testing, Kevlar-Polyester (30-70)%, Carbon-Polyester (30-70)%, Glass-Polyester (30-70)%, Kevlar-Polyester (40-60)%, Carbon-Polyester (40-60)% and Glass-Polyester (40-60)%. Practical implications: On the experimental part, experimental work tests were carried out to determine the mechanical properties of the samples such as tensile and compression tests as well as conducting the natural frequency test conducting the impact test by bullet to identify the effects and penetration incidence and compare this with the theoretical results. Originality/value: In this research high velocity impact is used with a bullet it diameter 9 mm, mass of 8 g, and a semi-circular projectile head with a specific velocity ranging from 210-365 m/s. The effect of the impact is studied theoretically and experimentally. The elastic deformation is increased for increasing the ratio of the fiber to the polyester and the depth of penetration is decreasing. The hybrid sample is affected in absorption energy and decreasing the penetration. Finally calculated for penetration behaviour theoretically and experimentally for different composite materials and comparison for the results calculated.

2

Experimental study of water tank under impulsive loading

Wang Y., Lee S. C.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 4

986--996

EN

The performance of stainless steel water tank subjected to impulsive loading was experimentally studied in this paper. The gas gun was utilized to activate the projectile with high impact velocity. The activated projectile then impinged the impact transfer plate which pressed the airbag behind it. The inflated airbag between the impact transfer plate and water tank was adopted to transfer the impulsive loading from impact transfer plate to the water tank. The ultra-thin pressure sensors were placed between the airbag and water tank to record the pressure imposed onto the water tank and the potentiometers were attached at the back of water tank to record the displacement histories. The water tanks with two different front and rear plate thicknesses were investigated. In addition, the same water tank with and without filled water was compared to study the water effects on the response of water tank under impulsive loading. Besides the experimental studies, the FE method was adopted to reproduce the experiment and improve the current test method. Finally, the experimentally verified FE models were further used to study the water effects in reducing the deformation of water tank under blast loading.

3

Experimental investigation of energy dissipation properties of fibre reinforced plastics with hybrid layups under high-velocity impact loads

Romano M., Hoinkes C., Ehrlich I., Höcherl J., Gebbeken N.

Journal of Achievements in Materials and Manufacturing Engineering

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2014

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Vol. 64, nr 1

5--19

EN

Purpose: The present work deals with the experimental investigation concerning the energy dissipation capacity of different kinds of reinforcement fibres in monolithic and hybrid layups under high velocity impact loads. The investigated kinds of fibres are carbon, glass and basalt. Design/methodology/approach: The test panels have been impregnated with thermoset resin. Curing was done by autoclave processing. In order to obtain comparable fibre volume contents of approx. 60 % in the different layups (monolithic and hybrid without and with separating layer), curing cycles adapted to the type of layup have been identified. The resulting fibre volume content of the test panels has been determined both by weighing and experimentally by chemical extraction and calcination. The impact load was applied by an instrumented experimental setup. Thereby both commercially available bullets and bearing balls accelerated with weighted propellant in a sabot have been used as impactors. The measured values are the velocities of the bearing balls as the impactor before and after penetration of the test panels. Findings: In both cases the results show the energy dissipation capacity of each single kind of fibre in case of the monolithic layups as well as the enhanced properties of the hybrid stacked layups without and with the separating layer as a core material. Typical failure modes on the impact surface and on the outlet areas are identified. Research limitations/implications: The influence of the respective kind of impactors, namely bullets and bearing balls, on the evaluated results is identified. Thereby the bearing balls exhibited a higher degree of reproducibility due to several reasons. Originality/value: Fibre reinforced plastics with hybrid stacking sequences can be used as load-bearing structures and at the same time as safety structures for passengers in automotive or aerospace applications. Moreover, with the hybrid stacked composites lightweight concepts can efficiently be realized regarding energy saving issues.

4

Układ do zsynchronizowanych pomiarów sygnałów z czujników tensometrycznych

Majcher A., Mrozek M., Przybylski J., Zbrowski A.

Problemy Eksploatacji

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2010

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nr 4

59-66

PL

W artykule przedstawiono rozwiązanie układu do zsynchronizowanego dynamicznego pomiaru sygnałów z rezystancyjnych czujników tensometrycznych. Synchronizacja korzysta z trzech metod: wyzwalania sygnałem cyfrowym (zdarzeniem), wykrywania odpowiedniej wartości mierzonego sygnału analogowego, wyzwalania sygnałem aktywacji, po którym następuje zmienny interwał czasowy do chwili odpowiedzi czujników. Scharakteryzowano każdą z metod w aspekcie zastosowania układu do pomiarów efektów uderzeń obiektów o dużych prędkościach. Opisany układ może znaleźć zastosowanie w monitorowaniu i analizie uszkodzeń, pracach związanych z dynamiką płynów i gazów, akustyką, badaniami wytrzymałościowymi materiałów i obiektów.

EN

The article describes system for synchronised measurements of signals from strain gauges. Synchronization utilises three methods: event driven triggering by digital signal, detecting the suitable value of measured analog signal, triggering by the starting of the pulse used to activate the actuator after which stochastic interval follows till the moment of the answer of sensors. The methods were characterised in terms of the application of the system in the measurement of impact effects of high velocity objects. The described system can be used in monitoring and fault detection, in works connected with dynamics of liquids and gases, acoustics, the analysis of materials the and objects damages.