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Volume 38 (2012)
- Issue 6 Pages 228-
- Issue 5 Pages 183-
- Issue 4 Pages 137-
- Issue 3 Pages 93-
- Issue 2 Pages 41-
- Issue 1 Pages 8-
Volume 38, Issue 6
Displaying 1-4 of 4 articles from this issue
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Research paper
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Kenichi HIRAI, Yoshiki MATSUURA, Kiyoshi KINEFUCHI, Toru KAMITA2012 Volume 38 Issue 6 Pages 228-235
Published: 2012
Released on J-STAGE: November 19, 2013
JOURNAL FREE ACCESSThis study focuses on the understanding and modeling of the physical phenomena occurring in the degraded zones of Silica Phenolic (hereafter referred as SiFRP) under exposure to high temperature gases when applied to liquid rocket engine (LRE) combustor. Although the understanding and modeling of the phenomena is supposed to be essential in designing LRE combustor, a few works done in this fields appear in the open literatures. Basically, it is well known that when heated, the pyrolysis reaction proceeds in the SiFRP, forming 3 distinct zones of charred, decomposed and virgin zone, respectively. The obtainable information for the thermal response of SiFRP at ground firing tests is classified in 2 categories. The first is the equilibrium state characteristics after long time elapsed from the burnout, namely, the degraded thickness distribution, which reflects 3-D information (combustor inner surface×thickness-direction) of heat load distribution over the entire combustor inner surface thanks to the highly insulating nature of SiFRP. The second is the transient characteristics with regard to the degraded zones propagation in the SiFRP, which can be detected by application of ultrasonic testing (UT) method. In this paper, the progress of in-depth phenomena of SiFRP and the physical variation were intentionally studied. We strive to clarify and specify the quantitative threshold values of the interface points which characterizes each degraded zone and UT reflection point and eventually express the threshold values in terms of physical quantities that could appear in numerical analysis.View full abstractDownload PDF (7829K) -
Yukihiro KOSUGI, Takahira AOKI, Tetsuhiko MURAKAMI, Norio SASAGUCHI, A ...2012 Volume 38 Issue 6 Pages 236-243
Published: 2012
Released on J-STAGE: October 30, 2013
JOURNAL FREE ACCESSIn this study, fatigue tensile fracture characteristic and damage propagation mechanism of triaxially-woven fabric (TWF) composite are investigated experimentally. Static tension and tension-tension fatigue tests on the TWF composite are conducted at room and high temperature to acquire ultimate tensile strength, trends of the tangent stiffness and S-N curves. Damage initiation and accumulation mechanism are also discussed based on X-ray CT scans. It is experimentally verified that static and fatigue characteristic of TWF has dependence on hygrothermal condition and failure mechanism under tensile loading is highly related to matrix failure on the intersection of the yarns.View full abstractDownload PDF (2406K) -
Kyosuke KOSO, Yoshihiro TAKAO2012 Volume 38 Issue 6 Pages 244-253
Published: 2012
Released on J-STAGE: October 30, 2013
JOURNAL FREE ACCESSFiber reinforced plastics/metal hybrid laminates are composites laminated by fiber reinforced plastics (FRP) and light metals such as aluminum alloy. GLARE, one of the fiber reinforced plastics/metal hybrid laminates laminated by glass fiber reinforced plastics (GFRP) and aluminum alloy, has been applied to an upper fuselage panel in an Airbus A380. The precise stress distribution of the out of plane components has not been discussed around the contact hole boundary, though most of papers on the mechanical joint of GLARE deal with strength and damages. This paper deals a complicated non-linear analysis including elastic-plastic mechanical response, anisotropic material properties, lamination, contact and friction. Compared with the previous results about CARALL by the same author, it was obtained that some parameters, such as contact and friction between pin and the hole of laminates, affect the distribution and magnitude of stresses. Particularly, it is important that bend in thickness direction caused by plasticity of aluminum layer and resistance to bend by longitudinal stiffnesses of FRP layer affects the out of plane normal stresses of the interface between AL layer and FRP layer or between FRP layers. On the basis of these results, we discussed the initial failure of a pin joint occurred at the part of net-tension of the joint.View full abstractDownload PDF (3719K) -
Makoto ICHIKI, Hiroshi SUEMASU, Yuichiro AOKI2012 Volume 38 Issue 6 Pages 254-261
Published: 2012
Released on J-STAGE: October 30, 2013
JOURNAL FREE ACCESSIn the present paper, compressive behavior and failure mechanism of quasi-isotropic CFRP laminates with impact damage are studied numerically by a finite element method. The impact damage is modeled as a double-spiral-shape damage consisting of pairs of fan-shape delaminations and transverse cracks which links the delaminations above and below the lamina. The results of the geometrically nonlinear analysis show that the post-buckling behavior comprises three stages; buckling of thin damaged portions near the surfaces, buckling of the whole damaged area (through-thickness buckling) and global bucking. Stress concentration in 0 layer was caused at the transverse direction against the load. The energy release rate distribution was calculated by the virtual crack closure technique (VCCT) along the whole delamination tips. The energy release rate of the every transverse direction rapidly increased after through-thickness buckling of the damage portion. The increasing curves of maximum energy release rate with increasing compressive load well correlated with the relationship between the compression-after-impact (CAI) strength and the mode II interlaminar fracture toughness of various laminates. The final failure of the impact damaged laminates is probably caused by simultaneous growth of the all delaminations to the transverse direction when the interface of laminates is not very brittle.View full abstractDownload PDF (2525K)
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