Full-Field Strain and Temperature Measurement of Epoxy Resin PR-520 Subjected to Tensile Loading at Various Strain Rates
Loading...
Date
2018-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
Increasingly, aircraft engine manufacturers are turning towards composite materials for use in various engine components; more specifically the fan case surrounding the engine. The high strength, high stiffness, and low weight of composites make them a competitive alternative to traditional aircraft materials such as aluminum and titanium. Composites in fan case applications have become an important topic of research because regulations require that an aircraft engine case must be able to contain debris resulting from a blade out type engine failure. Once the impact characteristics of these composite materials are determined, a blade out engine failure can be simulated through a computational model, potentially reducing time and cost of designing and manufacturing composite fan cases. The properties of the polymer matrix of the composite become important in impact situations when the force is applied out-of-plane with respect to the composite fibers, and the polymer matrix is the primary factor affecting the strain rate dependency of the composite as a whole. Computational models including the rate dependent effects of the matrix material exist, but they neglect the coupling of the thermal and mechanical responses of the material. The purpose of this study was to simultaneously measure the full field thermal and full field deformation response of epoxy resin PR-520 in tensile tests conducted at strain rates of 0.01s-1, 1.0s-1, and 350s-1. 2-D and 3-D digital image correlation was used for full-field measurement of deformation, and high-speed infrared thermography was used for full-field temperature measurement. The testing was conducted on two test apparatus, a servo-hydraulic load frame for the low and intermediate rate tests, and a direct tension Split-Hopkinson bar for the high rate tests. The results show a coupling between temperature change and strain in the test specimens, with cooling occurring during elastic deformation, and heating occurring during plastic deformation. The results also show a dependence of both thermal and mechanical response, on strain rate. The data generated by the tests can be used to modify the constitutive equations for the matrix material to allow better prediction of characteristics such as failure strain, strength, and fatigue.
Description
Keywords
Polymers, Thermomechanical Response, Full-Field Temperature, Full-Field Deformation, High Rate