1,721,002 research outputs found
Mechanically fastened composite side-door impact beams for passenger cars designed for shear-out failure modes
No full textThe fuel efficiency and emission gas regulations of passenger cars are two important issues nowadays. The best way to increase the fuel efficiency without sacrificing safety is to employ fiber reinforced composite materials in the body of cars because fiber reinforced composite materials have higher specific strengths than those of conventional steel or aluminum. In this study, a composite side-door impact beam for passenger cars was designed to reduce the weight of steel impact beam using glass fiber reinforced composite. The static bending tests of the beams were performed for the optimum fiber stacking sequence, followed by the static tensile tests of the joint between the composite beam and the brackets on the car body. In order to increase the energy absorption characteristics of the composite impact beam, the mechanical joint was designed to fail with fiber shear-out mode, from which the impact energy might be dissipated during the side-door collision of passenger cars. The manufactured composite impact beam was mounted on the real side-door of a compact passenger car and tested under static bending moment. From the test, it was found that the composite impact beam with 70% weight of a high strength steel beam had comparable static bending strength. (C) 2002 Elsevier Science Ltd. All rights reserved
Damage tolerance of composite toecap
No full textIn this study, the glass fiber polyester composite toecap for safety shoes was designed and manufactured to increase the energy absorption capacity during impact and to reduce the weight of steel toecap. The static compression and drop weight impact tests of 191 the composite toecap were performed with respect to stacking sequence, and the damage after impact was measured by macrography and CAI (Compression after impact) test. From the experimental results. it was found that the stacking sequence and fiber types of the composite toecaps had much influence on the static stiffness and impact damage of the toecap. The weight saving of the composite toecap was about 40% compared with the steel toecap of comparable static and impact characteristics. (C) 2004 Elsevier Ltd. All rights reserved
Failure modes of foam core sandwich beams under static and impact loads
No full textIn recent times, sandwich structures have been widely used in load bearing structures due to their high specific stiffness and high specific strength. Some sandwich structures, such as those used in high speed transportations, are required to have high impact energy absorption characteristics also. Since sandwich structures can fail in various modes, in this article, the static failure modes and load capabilities of foam core composite sandwich beams composed of E-glass/Epoxy and PVC foam were investigated by both experimental and analytic methods. The static load capabilities and failure modes predicted by the theory of beam on elastic foundation showed good agreement with the three-point bending test results. Using the experimental and analytic results, the static failure mode map was constructed. Also, the impact failure modes and the impact energy absorption characteristics of the sandwich beams were studied by the impact test and the finite element analysis. From the test result, it was found that the face failure mode was favorable for the high impact energy absorption. Using the experimental and finite element analysis results, the impact failure mode map was constructed
Impact energy absorption characteristics of glass fiber hybrid composites
No full textIn the present study, the impact energy absorption characteristics of glass fiber-reinforced hybrid composites were investigated by the instrumented Charpy impact test method with respect to the volume fraction of different materials embedded. Also, the interlaminar shear properties were measured by the short beam shear test to investigate the correlation between the interlaminar shear properties and the impact energy absorption characteristics. To predict the impact absorption characteristics of glass fiber hybrid composites, the progressive impact fracture model was proposed. (C) 1999 Elsevier Science Ltd. All rights reserved
Impact energy absorption characteristics of composite structures
No full textThe tensile and compressive tests of glass-epoxy composites with 1-200 s(-1) strain rates which are typical strain rate range during automobile crash accidents were performed in order to measure the strength variation with respect to strain rate. The tests were performed using both a horizontal type pneumatic impact tester and a conventional dynamic universal test machine with strain-rate-increase mechanisms. Also, the impact energy absorption characteristics of glass fiber reinforced composites were estimated using the newly proposed progressive impact fracture model. From the experiments and predictions, it was found that the proposed method predicted relatively well the experimental results. (C) 2000 Published by Elsevier Science Ltd. All rights reserved
Fatigue characteristics of the bolted joints for unidirectional composite laminates
No full textWhen composites are employed as structural materials, joining of composites to other materials is necessary because manufacturing structures with composites only is not generally feasible. Although the maximum static strength of the composite bolted joint is frequently realized by quasi-isotropic patterns, these patterns are seldom used in structural members under general load, such as bending, compressive, and tensile load. To increase the efficiency of whole structures with the composite bolted joints, the laminate with stacking sequence of [+/- theta/0(8)](s) was proposed in this work. The fatigue characteristics of the [+/- theta/0(8)](s) laminate bolted joint were investigated with respect to the angle 0 and the bolt clamping pressure and compared with the result of the [0(2)/+/- 453/90(2)](s) laminate, which was proposed as one of the optimum stacking sequence under the static load. From the experiments on the bolted joints, it has been found that the laminates whose major plies are stacked in the axial direction can be used for the bolted joint structures under fatigue load when an appropriate clamping pressure is applied to the bolted joint. (C) 2004 Elsevier Ltd. All rights reserved
Foreign objects impact damage characteristics of aluminum/composite hybrid drive shaft
No full textIn this work, the low velocity impact damage characteristics of aluminum/composite hybrid drive shaft were investigated. The hybrid drive shaft was manufactured by stacking carbon epoxy composite prepregs and insulating layer for galvanic corrosion on the inner surface of an aluminum tube, and co-curing them in an autoclave under recommended cure cycle. After impacting the co-cured hybrid drive shafts using a drop-weight impact tester, the damage and delamination of the composite layers were observed with an ultrasonic C-scan, from which the damage modes of aluminum/composite hybrid shaft were found with respect to the stacking sequence of composite materials, the thickness of the aluminum tube and the impact energy. Finally, optimal stacking sequence of the composite material and optimal thickness of the aluminum tube for the drive shaft for low velocity impact were suggested. (C) 2004 Elsevier Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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