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Rani Elhajjar
Additive Manufacturing of Aerospace Composite Structures: Fabrication and Reliability introduces the reader to the current state of technologies involved in processing and design of polymer-reinforced fiber composites using additive manufacturing’s automated fiber placement methods, through ten seminal SAE International papers. Currently, the material layup strategy in terms of process selection and manufacturability is usually not prioritized in the design phase. Engineers do not have a good way to see how their design choices can affect the manufacturing process beyond their initial structural-level considerations. The result is typically a large amount of experimental testing necessary to qualify the materials and structures typified in the classical building-block approach. Such an environment makes mistakes difficult to solve and, should redesign be required, obtaining reliable information is hard to piece together.
Journal Article
Seyedmohammad Shams, Peng Yang, Rani Elhajjar
Abstract The disk spring offers the potential of significant weight savings when designed with continuous fiber reinforced composite materials. The internal stresses in a disk spring are ideally suited for composite material application due to their superior resistance to in-plane and bending stresses. In this study, a composite laminate disk spring is designed, analyzed and fabricated to take advantage of the low specific strength and weight and high damage tolerance of composite laminates. The design of the disk composite spring considers effects of the laminate stacking sequence and the geometric variables on the disk spring's mechanical performance. A continuum damage finite element analysis approach is used to understand the damage initiation and evolution as a function of applied load. Experimental analysis and a progressive damage analysis based on virtual crack closure technique are performed to evaluate the damage tolerance of the disk spring under fatigue loadings.
Journal Article
Kil Won Song, David Roehrich, Rani El-Hajjar
Fillet and plug weld are commonly used in structural applications in commercial heavy vehicles. This paper is primarily concerned with an investigation of the full field deformations fields in fillet and plug welds using three dimensional digital image correlation (3D-DIC). Two identical vehicle parts are constructed using a fillet weld for one specimen, and a plug weld for the other. The specimens are loaded under quasi-static conditions with simultaneous measurement of load, displacements and strain gage measurements. Strain gage locations are selected based on the results of a finite element analysis model. 3D-DIC measurements are constructed using a two camera setup. Thus, 3D-DIC measurements are compared to strain gage measurements and finite element predictions. The effectiveness of the non-contact full field method is evaluated for application to studying the weld details considered and potential for fatigue damage and durability.
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