Papers by Keyword: 3-Point Bending Test

Abstract: Recently, automobile components such as center pillars and impact beams have been fabricated using materials that satisfy both high strength and impact absorption. In this study, the forming process of CR340 (cold rolled steel)/CFRP hybrid composites was investigated. Initially, hybrid composites were fabricated by stacking carbon fibre reinforced plastic (CFRP) prepreg on CR340 steel with Zn coating. An adhesive agent developed by the research team was applied for bonding between the cold rolled steel and CFRP to enable the blank fabrication of hybrid composites. The mechanical properties of the developed hybrid composites were investigated by tensile, bending and lap shear adhesion test. The results showed that the tensile strength and shear strength of composites increases with the increase in the number of laminations but the bending strength decreases.

Abstract: We have focused on shape-memory properties of Cu-Sn based ternary alloys in this study. We have attempted to suppress degradation at room temperature aging and to improve the amount of shape recovery by adding the third element to a binary Cu-Sn alloy. The attempt has successfully conducted in Cu-Sn-Mn alloy, the degradation due to aging at room temperature was suppressed and the thermal stability was improved. Furthermore, the present study revealed that Cu-Sn-Mn alloy exhibited a large super elastic recovery in three point bending tests. We have also investigated the shape-memory properties of Cu-Sn-Si alloys and revealed that the ternary alloy has achieved super-elastic recovery better than the Cu-Sn-Mn alloy in the three-point bending tests.

Abstract: In this study, guide sleeves are brought into 3D weaving composite preforms. The process vacuum assisted resin infusion (VARI) was used to fabricate the 3D weaving composite with guide sleeves. The load-deflection curves and shear behaviors of the 3D weaving composites with guide sleeves were obtained by means of the 3-point bending test. The fracture micrographs of the materials were studied by SEM. The effects of guide sleeves’ diameter and interval on the shear behavior and fracture mechanisms of the 3D weaving composites were analyzed. The results showed that the guide sleeves could prevent delamination effectively by bridging fiber layer and pinning crack extending along the fiber layer. Fracture toughness of the composite parts increase because of deformation, fracture of guide sleeves and debonding of interface. The diameter and interval of guide sleeves is smaller, which means the volume fraction of guide sleeves is higher, the interlaminar shear strength higher for the bridging is stronger.

Abstract: In this paper, the correlation between structural and mechanical properties of nanostructured austenitic oxide dispersion strengthened (ODS) steel prepared by powder metallurgy were studied. High efficient milling process was applied to achive an optimal dispersion of ceramic oxide particles in the steel matrix. The austenitic powder with or without Y₂O₃ addition was milled by two different milling process (wet and dry). Spark plasma sintering as a fast and effective compaction method was used as sintering equipment. The morphology and structural properties of ODS were studied by X-ray diffraction and scanning electron microscopy. Mechanical properties, such as microhardness, bending strength and modulus of nanostructured ODS were also determined.

Abstract: Metallic closed cellular materials containing polymer were fabricated by the penetrating polymer into metal foam. The aluminum and stainless steel foams were selected for the metal foam and epoxy resin and polyurethane resin were selected for the penetrated polymer. The many kinds of mechanical properties of this material were measured. The results of the compressive tests show that these materials have different stress-strain curves among the specimens that containing different materials in the cells. Also, this metallic closed cellular materials containing polymer have higher compressive strength, higher Young’s modules, higher energy absorption and higher internal friction than that of metallic closed cellular material without any polymer.

Abstract: Impact behaviors of Aluminum Honeycombs Sandwich Panel (AHSP) by drop weight test were investigated in this study. Two types of specimens with l/2" and l/4" cell size were tested by two impactors with the weight of 5.25kgf and 11.9kgf respectively. Transient, contact and elastic-plastic analyses were performed by finite element method. Impact behavior of AHSP about impact sites appeared nearly the same in low impact energy, but it was different in high impact energy. Face was the strongest about impact and short-edge was the weakest. The damaged area of AHSP was enlarged with the increase of impactor weight that is corresponding to impact energy. After 3-point bending test, fracture modes of AHSP were analyzed with AE counts, lower face sheet was fractured in the long-edge direction first, and then separation between face sheet and core happened. In the short-edge direction after core wrinkled, lower face sheet was torn, impact behavior by FE analysis were increased localized damage in high velocity because the faster velocity of the impact was, the smaller the stress of core was. Consequently, impactor weight had an effect on widely damaged area, while the impact velocity gave rise to localized damaged area.