Khosravani, Mohammad Reza
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Publication Access status: Open Access , Brittle fracture of notched components fabricated by stereolithographySince additive manufacturing (AM, i.e., 3D printing) has been widely used for production of end-used products, the mechanical strength of parts fabricated by this technology have gained considerable significance. The current study presents fracture load assessment of 3D-printed components fabricated by the stereolithography (SLA) technique using UV sensitive resin material. In this context, dumbbell-shaped specimens were printed and tested to determine basic mechanical properties. Moreover, V-notched semi-circular bending test coupons with various notch opening angles (i.e., 15°, 30°, 45°, 60°, 75°, and 90°) were printed and examined. Parallel to the experimental tests, we developed a finite element model to simulate the load carrying performance of 3D-printed parts. Moreover, we used the digital image correlation technique to determine displacement and strain field on the surface of the examined specimens. Since the mechanical strength and fracture behavior of 3D-printed parts are investigated in the current study, the presented outcomes can be utilized for innovative designs of parts fabricated by SLA with a higher mechanical strength, and improved load-carrying capacity.Source Type:Article7 11 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Effects of steps on the load bearing capacity of 3D-printed single lap jointsDamage in adhesively bonded joints typically initiates in the overlap area due to high level of bonding (peel) stress. Different approaches are being considered to decrease the peel stress and improve the overall strength of the joint. One possible approach is to shape the over lap area into a stepped form configuration and enhance the performance of the joint. In the current study, we investigate effects of stepped-shape overlap area on the load bearing capacity of additively manufactured single-lap joints. To this aim, stepped-lap adhesively bonded joints with different designs and geometries in the overlap (bonding) area are considered with 3D-printed polylactic acid (PLA) adherends using the fused deposition modeling (FDM) process. Three configurations with different step sizes are considered to manufactured a set of adhesively bonded single-lap joints and to investigate the optimum length of the steps. The results are compared with our previous experimental findings on 3D-printed conventional single-lap joints. The obtained outcomes reveal that creating steps in the overlap area has a significant influence on the structural integrity and fracture load of 3D-printed adhesive-bonded joints and the bonded structures with identical step size in boding area reveal a better performance in load carrying capacity and shows a higher fracture load. Parallel to the experimental practices, a finite element model also developed to simulate the load carrying performance of the adhesively bonded singlelap joints with equal step size and 3D-printed PLA adherends. The FE model confirms the experimental outcomes and reveals the details of the cohesive failure and damage evolution mechanism in this bonded structures with PLA printed adherends. The proposed technique has a great potential to be a competitive alternative to conventional single-lap joints made by 3D printing. The presented results can be used for further fabrication of 3D-printed joints with a better structural performance.Source Type:Article2 15 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , On the Pin-Bearing Strength of Additively Manufactured Polymer PartsDue to the wide scope of applications of additive manufacturing (AM) in making final products, the mechanical strength of AM parts has become very important. Therefore, different tests are being developed to determine the structural integrity of three-dimensional printed components. In this respect, the pin-bearing test is designed to evaluate the response of a fastener, plate, and hole to stress. In this study, two different polymer materials were used to fabricate the samples utilizing the fused deposition modeling technique. Since the specimen width and hole diameter have effects on the pin-bearing strength and structural integrity of the parts, we prepared the specimens with four hole diameters to determine the influence of this ratio. A series of tensile tests were performed, and the stiffness and pin-bearing strength of additively manufactured specimens were determined. The preferred bearing failure mode was observed in several tested specimens. Subsequently, a scanning electron microscope investigation was conducted on the damaged area of the examined specimens to obtain insights into the damage mechanisms and failure behavior of the aforementioned specimens. We used digital image correlation technique to determine the strain field of dumbbell-shaped test coupons. The results of this research can be utilized for new designs of AM parts with a higher mechanical strength.Source Type:Article2
