Study of Biaxial Fatigue Behavior of Fiber Reinforced Polymers Under Tensile and Shear Loadings

Fatigue;Fiber reinforced composites;Arcan;Automotive Systems Engineering;Automotive Systems Engineering, College of Engineering and Computer Science

Mandapati, RaghuramReyes-Villanueva, German ;

University of Michigan

关键词: Fatigue;    Fiber reinforced composites;    Arcan;    Automotive Systems Engineering;    Automotive Systems Engineering, College of Engineering and Computer Science;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/136076/Mandapati%20Final%20Approved%20Dissertation.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Fiber reinforced polymers are used in many structural applications in the aerospace and automotive industries because of their high strength to weight and highmodulus to weight ratios. In many of these applications, they are used as thin laminatedpanels comprising of multiple layers of continuous fibers embedded in a polymer matrix.In general, these laminates behave as an orthotropic material and their properties aredirection-dependent. While their uniaxial static and fatigue characteristics have beenstudied extensively, their biaxial static and fatigue characteristics are not well established.One reason for this is the difficulty of conducting biaxial tests, especially under cyclicloading conditions. The objectives of the current research are two folds: (1) develop abiaxial test method that can be applied to a range of normal and shear loadings, and (2)study the biaxial fatigue behavior of a fiber reinforced polymer laminate using the newtest method.The test method developed in this research is based on a butterfly-shaped Arcanspecimen. The versatility of the Arcan specimen is that it can be utilized for testingmaterials under uniaxial normal loading, shear loading or a combination of in-planenormal and shear loadings. The laminate considered in this study was a [0/90/04/0]S Eglass/epoxy.Finite element analysis of a butterfly-shaped Arcan specimen was conducted first to establish its optimum geometry and delineate the importance of the stiffness of the test fixture on the stresses in the significant section of the specimen. AnArcan loading fixture was designed with the capability of loading of flat laminatespecimens under various combinations of in-plane tensile and shear stresses. Quasi-staticand fatigue tests were conducted with four different specimen configurations containingeither 0, 30, 45 or 90o fiber orientations in the outer layers. The quasi-static strength followed a quadratic failure envelope on a normal stress-shear stress plane. Biaxialfatigue tests were conducted under combined tensile and shear stresses to determine theeffect of biaxiality on the fatigue performance of the laminate. Development of fatigue damage under biaxial loading was also studied. A new fatigue life prediction model wasproposed that can be used to account for the effect of biaxiality on the fatigue life of fiberreinforced polymer laminates.