The article presents the results of tests on selected strength properties of layered composites (laminates) based on an epoxy resin matrix with various types of fiber reinforcement. The influence of the type of material used for reinforcement on the mechanical properties of the composite was evaluated. The operating conditions of aircraft mean that composite structures are exposed to transverse impact loads, the visual effects of which are often invisible, yet they cause significant weakening of the material. The specific characteristics of laminates mean that these materials require the development of new methods for assessing their suitability for operation in conditions that pose a risk of impact damage. A method for testing the influence of impact loads on mechanical properties is presented, as well as an algorithm that takes into account that delamination and cracking are the main causes of the decrease in laminate strength after impact loading.THE TEST PROCEDURES TO DETERMINING STRENGTH PROPERTIES OF PLIED COMPOSITE WITH DIFFERENT REINFORCEMENT
The paper presents experimental results tests of selected mechanical properties (tensile strength, flexural strength, impact strength) of plied composites made of epoxy resin and different reinforcement fibers. Aircraft’s usage conditions bring about exposing composite structures to low-energy-level impacts. Effects of the impact are usually invisible during macroscopic observation but they cause a crucial decrease in material strength. Specific properties of laminates make that the materials require to work out new methods of evaluation their suitability for work in conditions propitious to appear low-energy-level impacts. The paper presents an investigation method of influence low-energy-level impact on mechanical properties and an investigational programme providing that delamination and cracking are main reasons of laminate strength reduction after impact. (…)
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Source: Logistyka Magazine