657 research outputs found
Mode II interlaminar fracture behavior of carbon bead-filled epoxy/glass fiber hybrid composite
No full textTo investigate the effect of including carbon beads on the mechanical properties of epoxy resin, the fracture toughness of carbon bead-filled epoxy was earlier evaluated using a CT (compact tension) specimens and Mode I fracture toughness was observed. Based on those results, in this study, the Mode Il interlaminar fracture toughness of carbon bead filled epoxy/glass fiber hybrid composites was evaluated using end notch flexure (ENF) specimens. The hybrid composites showed increased Mode II interlaminar fracture toughness. The optimal bead volume fraction was around 15%
Arbitrariness of asymmetric hat-type channel members in the axial crush
No full textThis paper is concerned with the crashworthiness of asymmetric hat-type specimens that are fabricated by spot welding or laser welding with different spacing between two welded spots. The specimens are evaluated for the axial crush at the various crush velocity. The experimental result shows that the specimens are not deformed in a consistent manner, but arbitrarily. In this type of axial crush, the length of the flange region is an important parameter as well as the spacing between welded spots. Experimental results also show the difference in. the crush mode between the spot-welded specimens and the laser-welded ones. The difference in the first peak and average load is also demonstrated as well as the energy absorption capacity
Modelling of crystal growth process in heat exchanger method
No full textTransient two-dimensional model of bismuth germanium oxide (EGO) crystal growth by the heat exchanger method has been developed. The moving boundary problems for the melt/solid interface location, the temperature field in the whole calculation domain and the flow held in the melt were solved by the two mapping rule method, which enabled the simulation of the melt/solid interface, changing from hemispherical to planar shape. The maximum deflection of the interface was observed when the melt/solid interface is at the corner of crucible. The effects of the various growth parameters were studied on the interface shape, the temperature profile and the stream function using this model. As the excess heating temperature was increased, the maximum deflection of the interface decreased. The heal exchanger temperature hardly affects the maximum deflection of the melt/solid interface. The maximum deflection of the melt/solid interface is not very sensitive to the value of the thermal conductivity of the melt of EGO
EXPERIMENTAL-VERIFICATION OF SUPERPLASTIC SHEET-METAL FORMING ANALYSIS BY THE FINITE-ELEMENT METHOD
No full textThe numerical result for superplastic sheet-forming simulation is compared with the experimental result to verify the validity of the finite-element code developed. The code calculates the optimum pressure cycle, the deformed shapes, and the distributions of the strain and strain-rate in the blow-forming processes. The calculation deals with the maximization of the strain-rate sensitivity, the protection of the localized deformation, the consistency of the desired strain-rate, and the control of the hour-glass mode and locking phenomenon. The comparison demonstrates the validity of the present algorithm and its results, especially in respect of the optimum pressure cycle, where there is only a slight difference between the two results
The mechanical behavior of optical fiber sensor embedded within the composite laminate
No full textMechanical behavior, such as tensile and fatigue strength, of the optical fiber sensor embedded within the composite laminate was investigated. Tensile and fatigue tests were performed to evaluate the static and fatigue characteristics of optical fibers embedded within three types of laminated composite specimens, [0(6)/OF/0(6)](T), [0(2)/90(4)/OF/90(4)/0(2)](T) and [0(3)/90(3)/OF/90(3)/0(3)](T). The initiation of damage and fracture of the optical fiber were detected by observation of the intensity drop-off of laser signal transmitted through the optical fiber during test. Experimental results showed that the fatigue strength of optical fiber embedded within the cross-ply laminate is much lower than the fatigue strength of optical fiber within the unidirectional ply laminate. It was also found that the optical fiber embedded within unidirectional ply laminate fractured due to the fatigue damage accumulation of internal defects of optical fiber itself. However the optical fiber embedded within the cross-ply laminate fractured due to the growth of transverse matrix crack of host composite laminate. (C) 1999 Kluwer Academic Publishers
Low velocity impact and delamination buckling behavior of composite laminates with embedded optical fibers
No full textA drop-weight impact test and delamination buckling test were performed to investigate the development of impact damage and post-impact compression behavior of cross-ply composite laminates with optical fibers embedded in the interface of two different angle plies. It was found that the presence of optical fibers had little or marginal effect on the shape and size of damage area of the laminate when the optical fibers were embedded parallel to the host reinforcing fibers. Non-parallel optical fibers promoted unstable crack growth through the formation of resin rich regions, which in turn increased slightly the impact damage area. It was also shown that a large number of parallel optical fibers may have an ameliorating effect on delamination buckling strength as they promote the waviness of the delamination fracture surface
Effects of HCV replication on cell proliferation of Huh-7.5.1 and HuH-7T1.
No full text<p>(A) Population of HCV-positive cells after JFH-1 RNA transfection. Two micrograms of JFH-1 RNA was electroporated into Huh-7.5.1 and HuH-7T1 and cultured with or without 10 mg/mL of anti-CD81 antibody (clone JS-81, BD). Cells were harvested at Days 1, 3, and 5. After fixing, cells were stained with anti-NS5A antibody and analyzed by flow cytometry. (B, C) Cell cycle distribution of HCV-positive and -negative cells after JFH-1 RNA transfection. Two micrograms of JFH-1 RNA was electroporated into Huh-7.5.1 and HuH-7T1. Cells were pulse-labeled with EdU and analyzed for cell cycle distribution. The percentages of cells in G0/G1, S, and G2/M phases of the cell cycle were calculated by gating with FlowJo software. (B) Representative cell cycle distributions of HCV-negative and -positive cells. (C) Percentages of cells in each phase of the cell cycle for HCV-negative and -positive populations. Assays were performed three times independently; data are presented as mean ± standard deviation.</p
DESIGN OF THE CROSS SECTION SHAPE OF AN ALUMINUM CRASH BOX FOR CRASHWORTHINESS ENHANCEMENT OF A CAR
No full textThis paper deals with the crashworthiness of an aluminum crash box for an auto-body with the various shapes of cross section such as a rectangle, a hexagon and an octagon. First, crash boxes with various cross sections were tested with numerical simulation to obtain the energy absorption capacity and the mean load. In case of the simple axial crush, the octagon shape shows higher mean load and energy absorption than the other two shapes. Secondly, the crash boxes were assembled to a simplified auto-body model for the overall crashworthiness. The model consists of a bumper, crash boxes, front side members and a sub-frame representing the behavior of a full car at the low speed impact. The analysis result shows that the rectangular cross section shows the best performance as a crash box which deforms prior to the front side member. The hexagonal and octagonal cross sections undergo torsion and local buckling as the width of cross section decreases while the rectangular cross section does not. The simulation result of the rectangular crash box was verified with the experimental result. The simulation result shows close tendency in the deformed shape and the load-displacement curve to the experimental result
Axial crush and bending collapse of a aluminum/GFRP hybrid square tube and its energy absorption capability
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