Experimental Determination of the Coefficient of Restitution for Selected Modern Hybrid Composites

Abstract

Composite materials (fiber reinforced plastics, FRPs) are successfully utilized in the production of various mechanical devices, including land vehicles, marine vessels, and aircrafts. They are primarily used for the production of body parts and hulls. Due to their importance, certain requirements relating to the mechanical properties of the materials used must be met for such applications. One aspect of the passive safety of vehicles is the effects of a possible collision with another object. The behavior of the structure in such a case can be determined based on the coefficient of restitution, which is a measure of energy dissipation after an impact. This paper presents the results of measuring the value of the coefficient of restitution for the selected composite materials, utilizing various reinforcement materials including different types of fibers and wooden veneer. The selected materials included glass, carbon, Kevlar fibers, and veneer from exotic wood in an epoxy resin matrix. The tested samples were made using various methods in order to understand the influence of the technology on the value of the coefficient. The authors determined the coefficient values utilizing two methods based on the measurement of two different physical quantities. In the first case, the height of the rebound of the ram was measured using a fast digital camera; in the second case, the time between successive rebounds of the tool was measured, determined based on the signal from the acceleration sensor. The authors compared the results of the coefficient values obtained using these methods and examined the relationship between the rebound energy and the value of the coefficient of restitution. The results have been discussed, and some conclusions have been made. Among other things, it seems that both methods of measurement are interchangeable with regard to lower impact velocities corresponding to lower heights (up to 300 mm) of the drop of the ram used in the tests.

Bondline Thickness Effects on Damage Tolerance of Adhesive Joints Subjected to Localized Impact Damages: Application to Leading Edge of Wind Turbine Blades

“…Note that COR can vary between 0 and 1 for elastic plastic impact, where COR = 1 corresponds to an ideal elastic impact, and COR = 0 corresponds to a perfectly plastic impact [65][66][67]. In addition, it has been found in the literature [65][66][67] that COR depends upon impact velocity as well as size and shape of the impacting surface and is also related to the energy loss percentage (%∆D) in the system [66] during the impact as:…”

Exploring factors affecting the conversion of the coefficient of restitution to equivalent free fall drop height

“…It is first used in the building field, including sand 1 and concrete, 2 then applied to pipes 3 and metal sheets 4 and finally used in packaging engineering. 5 The impact object, [6][7][8] impact base, 9,10 impact velocity, [11][12][13][14] number of impacts 15,16 and impact orientation 17 all have an influence on the COR. There are three primary categories: displacement COR, 1,4 velocity COR 12,15 and energy COR.…”