Purpose -This paper aims to define the effect of specimen mesostructure on the monotonic tensile behavior and tensile-fatigue life of layered acrylonitrile butadiene styrene (ABS) components fabricated by fused deposition modeling (FDM). Design/methodology/approach -Tensile tests were performed on FDM dogbone specimens with four different raster orientations according to ASTM standard D638-03. Resulting ultimate tensile stresses (UTS) for each raster orientation were used to compute the maximum stress for fatigue testing, i.e. 90, 75, 60 and 50 or 45 per cent nominal values of the UTS. Multiple specimens were subjected to tension -tension fatigue cycling with stress ratio of R ϭ 0.10 in accordance with ASTM standard D7791-12. Findings -Both tensile strength and fatigue performance exhibited anisotropic behavior. The longitudinal (0°) and default (ϩ45/Ϫ45°) raster orientations performed significantly better than the diagonal (45°) or transverse (90°) orientations in regards to fatigue life, as displayed in the resulting Wohler curves. Practical implications -Raster orientation has a significant effect on the fatigue performance of FDM ABS components. Aligning FDM fibers along the axis of the applied stress provides improved fatigue life. If the direction of applied stresses is not expected to be constant in given application, the default raster orientation is recommended. Originality/value -This project provides knowledge to the limited work published on the fatigue performance of FDM ABS components. It provides S-N fatigue life results that can serve as a foundation for future work, combining experimental investigations with theoretical principles and the statistical analysis of data.
A study of the cyclical fatigue behavior of additive manufactured components, fabricated by the fused deposition modeling (FDM) process, is presented. Experimentation was designed to focus on the effect of deposition strategy or specimen mesostructure on tensile fatigue life and effective stiffness. Testing included consideration of unidirectional laminates with parallel plies having fiber orientations ranging from = 0° to = 90°, and bidirectional laminates with alternating orthogonal plies that form a layering pattern of °/(-90°) fiber orientations. Results highlight the orthotropic behavior of FDM components and suggest that tensile performance is improved by aligning fibers of unidirectional laminae more closely with the axis of applied stress. The bidirectional laminae display incrementally improved tensile fatigue performance from what appears to be an offsetting effect associated with alternating orthogonal layers. An empirical model of effective elastic modulus and an analytical model of the accumulated damage state, as defined on the basis of stiffness degradation during cyclical loading, are presented as functions of specimen mesostructure. The actual damage accumulation due to cyclical loading is compared with the model predictions, and the coefficient of determination R 2 indicates reasonable agreement for each factor combination.
The stress corrosion cracking (SCC) behavior of two developmental nanocrystalline 5083 alloys with varied composition and processing conditions was studied. The results were compared to a commercial aluminum AA 5083 (H111) alloy. The pitting densities, size and depths, and residual tensile strengths were measured after alternate immersion in artificial seawater and atmospheric exposure under different loading conditions. Optical and scanning electron microscopy (SEM) with EDX was used to analyze the fracture surfaces of failed specimen after removal at selected intervals and tensile testing. One of the nanostructured Al-Mg alloys exhibited significantly superior pitting resistance when compared to conventional microstructured AA 5083. Under conditions where pitting corrosion showed up as local tunnels toward phase inclusions, transgranular cracking was observed, whereas under conditions when pitting corrosion evolved along grain boundaries, intergranular cracking inside the pit was observed. Pit initiation resistance of the nano alloys appears to be better than that of the conventional alloys. However, long-term pit propagation is a concern and warrants further study. The objective of this investigation was to obtain information regarding the role that ultra-fine microstructures play in their degradation in marine environments and to provide insight into the corrosion mechanisms and damage processes of these alloys.
Parts formed using fused deposition modeling (FDM) can vary significantly in quality depending on the manufacturing process plan. Altering the plan profoundly affects the character of the resulting part. Although the designer and the machine user may have preferences regarding the part build and the relative importance of build outcomes such as production speed, dimensional accuracy, and surface quality, setting process variables to ensure desired results is a complex task. A multi‐objective decision support system has been developed to aid the user in setting FDM process variables in order to best achieve specific build goals and desired part characteristics. The method uses experimentation to quantify the effects of FDM process variables on part build goals, and to predict build outcomes and expected part quality. The system offers the user the ability to quantify the trade‐offs among conflicting goals while striving towards the best compromise solution.
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