Papers by Keyword: Laminates

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Authors: Zhen-Yan Deng, Guo Jun Zhang, Motohide Ando, Tatsuki Ohji
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Authors: Kouichi Yasuda, Tadachika Nakayama, Satoshi Tanaka
Abstract: A mechanical model is proposed to estimate internal stress during sintering of ceramic multiphase laminates. A symmetrical multi-layered laminate is assumed, and one-dimensional elastic analysis is carried out on the change in stress of each layer during sintering, based on the differences in sintering strain, thermal expansion strain and phase transformation strain between the layers. By taking a limit such that the thickness of each layer approaches infinitesimally small, the internal stress expression can be extended into the case of the materials with continuous compositional change (viz. functionally gradient materials).
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Authors: Kouichi Yasuda, Pei Ling Lv
Abstract: This paper proposes a model for estimating stress history during sintering of ceramic laminates. A symmetrical 3-layered laminate is assumed, and one-dimensional elastic calculation gives the stress change of each layer during heating, keeping at the sintering temperature, and cooling, respectively. How to get the stress history is actually shown by incorporating data of mechanical and thermal expansion properties of calcined monolayers. The validity of this model is discussed with a preliminary experiment on dense alumina / porous alumina laminates.
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Authors: Hiroshi Asanuma
Abstract: A new designing concept to realize multifunctional structural material systems is proposed and demonstrated in this paper. The concept can be explained as follow: There exist a couple of competitive structural materials which normally compete with each other because of their similar and high mechanical properties, and they tend to have secondary properties which are different from each other or opposite among them. So if they are combined together to make a composite, the similar properties, normally high mechanical property, can be maintained, and the other dissimilar properties conflict with each other, which will generate functional properties. According to the proposed concept, a CFRP (carbon fiber reinforced plastics)/aluminum laminate was fabricated and its actuation capabilities and multifunctionality were successfully demonstrated. A titanium fiber/aluminum matrix composite was also fabricated, where the fiber was oxidized for electrical insulation and strengthening. This material system is very simple, but it can generate many useful functions such as heating, actuation, temperature sensing, deformation sensing and healing.
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Authors: Wei Liu, Gui Qiong Jiao, Jing Guo, Hao Tian Jiang
Abstract: Z-pins reinforced 2D ceramic matrix composites (CMCs), integratedly designed new materials, are developed to enhance 2D CMCs through-thickness in the form of Z-pins and to ensure significant increase in interlaminar fracture toughness, delamination resistance and impact resistance, and Z-pins reinforced 2D CMCs have much application. A manual pre-stitching method is developed to make holes in the graphite fixture to control Z-pins row spacings and to introduce yarns of 3000 T300 carbon fibers bundle into a preform. Z-pins reinforced woven CMCs for research were manufactured successfully by repeatedly using chemical vapor infiltration (CVI) to infiltrate SiC matrix into woven preform and carbon fiber sutures. It is shown that this method of manufactured Z-pins reinforced woven CMC is feasible.
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Authors: Yu Gao, Nan Li, Bin Liu
Abstract: More and more advanced composite materials are used in mainly supporting structure of civil aviation; its airworthiness safety should be the focus of the research. Damage assessment is the key step in the general composite repair procedure. In this paper, the ANSYS calculating method is validated on the basis of classic laminate theory which could be used to calculate composite strength. In one case, it is applied to simulation and modeling of the B767 landing gear door. The case shows that composite damage mode such as low velocity impact damage, curing and fatigue could be evaluated with finite element method, the result of evaluation is provided as a means to composite damage assessment. Thereafter, the finite element method can be used for structural health monitoring to advanced composites.
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Authors: L. Mosse, Wesley J. Cantwell, M.J. Cardew-Hall, Paul Compston, Shankar Kalyanasundaram
Abstract: The quality of the part and the robustness of the process in stamp-forming of sheet materials are determined by a number of variables. This study looks at the application of the stamping process to a Fibre-Metal Laminate (FML) material system and the effect of the process variables on the formability characteristics of these material systems. The effect of pre-heating temperature on the splitting and wrinkling behaviour has been investigated for two different FML systems. It has been found that different FML systems exhibit different failure modes.
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Authors: Soo Hyun Eum, Yun Hae Kim, Joong Won Han, Kook Jin Kim, Do Hoon Shin, Cheolmun Yim, Riichi Murakami
Abstract: To prove the suitability the honeycomb composites structure with VARTM, the mechanical properties of the skin materials and honeycomb composites structure were evaluated with the static strength tests. The mechanical properties of honeycomb composites structure made by VARTM were satisfied with the real using conditions instead of the composites structure made by autoclave process. Accordingly, the honeycomb sandwich composites made by VARTM is available for manufacturing various composites parts. VARTM was very effective method to manufacture the honeycomb sandwich composites. It was possible that the manufacturing process was changed from autoclave process to VARTM to solve the problems on the autoclave process.
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Authors: Ling Wang, Pu Rong Jia, Gui Qiong Jiao
Abstract: The tensile strength of carbon fiber reinforced resin matrix layer splice laminate was studied. Three specimens (M1.M2.M3) were cut from laminates with different joint location and the number of layer splice. Load schemes were performed and typical load-displacement curves of three specimens were recorded. The result shows that the joint location has seriously effect on the tensile strength and modulus of specimens. The tensile strength of M2 is obviously lower than that of M1 and M3. Furthermore finite element ABAQUS6.5 was also used to simulate the course of experimental test. The result shows that shear stress concentration occurs on the joint of model. The shear stress on the model M1 and M2 has the similar trend and concentrates in the middle of the joint area. And on the model of M3 the shear stress has a completely different trend from the M1 and M2 model. On the M2 the shear stress concentration is slightly higher than the other two. It indicates that the tensile strength of M2 is the lowest among the three models. So, the inter-laminar shear stress is the major factor leading tensile failure. The experimental tests are consistent with the finite element analysis.
351
Authors: Zdeněk Chlup, Hynek Hadraba
Abstract: Laminated materials are used for special applications where combination of properties of two components is needed. Ceramics is inherently brittle and above all superior properties (wear resistance, temperature durability, stiffness, low density and others) the brittleness is limiting factor for massive implementation in wide range applications. The laminated structure can be capable to overcome this handicap. Electrophoretic deposition (EPD) is the technique able to prepare ceramic laminated structures having strong interface between layers [1]. It is possible to prepare dense and crack free materials with tailored residual stresses controlled by layer thickness and deposition conditions by this technique. Crack propagation through layered composites based on Al2O3 and ZrO2 was studied. Cracks, produced by an indentation technique, propagated in direction to layer interfaces deflected towards the interface in the compressed layers and away from the interface in the layers containing tension stress [2,3]. Changes in the direction of crack propagation for the whole range of angles of incidence (0° - 90°) were described. The biggest change in the crack propagation was observed for the angle of incidence 45° for A/Z systems and was ca. 15°. The change in the crack propagation was independent on the level of residual stresses in the layers. Behaviour of indentation cracks observed in laminates under investigation was compared with the results obtained on standard SEVNB specimens having inclined the fracture plane with respect to the composite lamellar structure. This model condition helps to understand crack propagation in bulk material. All experimental work was supported by fractographical techniques enabling explanation of fracture micromechanism.
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