Composites and Functionally Graded Materials最新文献

{"title":"Automating the Design Process and Powder Processing of Functionally Gradient Materials","authors":"P. Kwon, M. Crimp, M. Chung","doi":"10.1115/imece1997-0653","DOIUrl":"https://doi.org/10.1115/imece1997-0653","url":null,"abstract":"\u0000 There is great deal of interest in Functionally Gradient Materials (FGMs) as evidenced by three recent international conferences on the subject (Yamanouchi, et al., 1990, Holt, et al., 1993 and Ishner and Cherradi, 1994). Similar to composites, FGMs are microscopically inhomogeneous. However, unlike most composites, macroscopic inhomogeneities are designed into FGMs. This is achieved by continuously varying the volume fraction of the second phase in a controlled manner. Thus, the distribution of the second phase has ‘to be designed’ based on the type of application and geometry of the structure. In addition, their inhomogeneous nature causes non-uniform shrinkage and cracks during processing before FGMs are ever put into service. Accordingly, two independent research programs are in progress on FGMs at Michigan State University; (1) fabrication technology and (2) design process management tools. On the former program, powder fabrication protocols are being developed to reduce processing-induced residual stresses. On the latter program, in a benchmark study for the framework developed by Baldwin and Chung (1995), the complete design process for axisymmetric FGMs cylinders is implemented.","PeriodicalId":104058,"journal":{"name":"Composites and Functionally Graded Materials","volume":"4674 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122048768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Creep Feed Grinding Parameters on Strength and Finish of Alumina","authors":"G. Sathyanarayanan, L. Plebani, H. S. Wang","doi":"10.1115/imece1997-0694","DOIUrl":"https://doi.org/10.1115/imece1997-0694","url":null,"abstract":"\u0000 The reliability of ground ceramics is affected by the subsurface cracks. Alumina was creep feed ground by utilizing a 25-1 fractional factorial design to vary the bond type, mesh size and concentration, feed rate, and depth of cut. The unit load, i.e., the normal force transmitted by each grit, was obtained from the normal grinding force and utilized to analyze the material removal mechanism and the observed roughness. The flexural strength is obtained from four point bending tests and correlated with unit load and surface finish. The study shows that creep feed grinding is best suited for alumina. Also the present study shows that fine mesh size and fast feed rate are recommended to grind alumina in order to obtain higher flexural strength.","PeriodicalId":104058,"journal":{"name":"Composites and Functionally Graded Materials","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122198421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanics of Polymeric Composites Exposed to a Constant Heat Flux","authors":"M. Tuttle, A. Mescher, M. L. Potocki","doi":"10.1115/imece1997-0660","DOIUrl":"https://doi.org/10.1115/imece1997-0660","url":null,"abstract":"\u0000 An analysis procedure is presented which can be used to model the behavior of a polymeric composite panel when subjected to both external loading as well as the high heat flux levels associated with a fire. The procedure accounts for the elastic and viscoelastic-viscoplastic response, thermal gradients and thermal stresses, and pyrolysis effects. Predictions based on estimated properties for an E-glass/polyester composite panel subjected to a uniaxial tensile stress of 240 MPa and a 1-D heat flux level of 10 kW/m2 are presented. The predicted response is considered to be a reasonable representation of the expected behavior.","PeriodicalId":104058,"journal":{"name":"Composites and Functionally Graded Materials","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129671734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ceramic Composites Technology Development for Industrial Applications at Babcock & Wilcox","authors":"R. Goettler, J. T. Keeley, R. Wagner","doi":"10.1115/imece1997-0680","DOIUrl":"https://doi.org/10.1115/imece1997-0680","url":null,"abstract":"\u0000 Babcock & Wilcox (B&W) and its parent corporation, McDermott International, Inc., comprise one of the world’s largest energy engineering and service companies. Included within the spectrum of it’s businesses are:\u0000 • fossil power generation systems, related environmental equipment and boiler cleaning products\u0000 • design engineering, structure fabrication, and equipment for offshore oil and gas production\u0000 • nuclear fuel and other nuclear propulsion components for the US Navy\u0000 • industrial heat exchangers and condensers\u0000 • automated work cells for material processing and inspection\u0000 • design of onshore hydrocarbon processing facilities\u0000 • environmental remediation services","PeriodicalId":104058,"journal":{"name":"Composites and Functionally Graded Materials","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125408299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stiffness Changes in Laminates Caused by Intralaminar Cracks and Shear Deformation","authors":"J. Varna, N. V. Akshantala, R. Talreja","doi":"10.1115/imece1997-0661","DOIUrl":"https://doi.org/10.1115/imece1997-0661","url":null,"abstract":"\u0000 An experimental study has been conducted to study stiffness changes in laminates containing inclined (off-axis) plies. The class of laminates studied is glass-epoxy (0, ±θ4, 01/2)s with θ = 25, 40, 55 and 70. It is found that for θ > 40 multiple cracks occur in the θ-plies while for θ < 40 no cracks are found. However, for all θ angles the laminate moduli change. A continuum damage mechanics approach is used to calculate stiffness changes due to cracks. In the absence of cracks the shear modulus reduction in the θ-plies, determined from independent tests on a (±45)s laminate, is found to provide good prediction of the observed stiffness changes.","PeriodicalId":104058,"journal":{"name":"Composites and Functionally Graded Materials","volume":"234 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125750319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Test Methods and Accelerated Testing for Life Prediction of Composite Systems","authors":"K. Reifsnider","doi":"10.1115/imece1997-0667","DOIUrl":"https://doi.org/10.1115/imece1997-0667","url":null,"abstract":"\u0000 If we wish to use a material for engineering purposes, we must answer three basic questions: how strong is the material, how stiff is the material, and how long will it last? Durability is defined by the answer to the third of these questions, and frequently takes the form of life prediction. The characteristics displayed by such a material under long-term conditions, such as resistance to creep, stress rupture, and fatigue, are quite different from, for example, metals. The life of composite systems is often determined by the accumulation of defects and damage, rather than by the occurrence or growth of such flaws. And the changes in stiffness and strength during that accumulation process may be quite large, of the order of 50 percent or more, before fracture occurs. Hence, it is necessary to consider large changes in the constitutive behavior of the materials if a representation or predictive model is to be constructed. Perhaps the greatest challenge associated with such an enterprise is the determination of the constitutive information that is needed to uniquely and completely define the long-term behavior of composite materials, especially under complex applied conditions, i.e., the determination of what to measure and how to measure it.\u0000 This paper will address the question of how to construct mechanistic models and related experiments that provide an interpretative link between the fundamental mechanical, chemical, kinetic, and thermodynamic processes that control the long-term behavior of composite materials and the remaining strength and life that defines durability and damage tolerance of those materials. The paper begins with the premise that any coherent philosophy must include a systematic and consistent analytical representation of all processes that define the evolution of properties and performance and of the resulting local stress states and material states that determine remaining strength and life. For the present case, kinetic theory, in a generalized form, is used to make such a construct. Then, we add the premise that the analytical representation must be cast in terms of constitutive quantities that are independent variables, i.e., that can be measured in the laboratory with experiments that produce unique and clearly defined physical constants, and that a canonical set of such constants can be defined. Finally, we address the question of how to actually measure such constants. At the heart of this discussion is the question of feasibility. A philosophy and attending model that requires the measurement of vast arrays of physical constants is not likely to be of interest to the applied community. And experiments that require some significant fraction of a lifetime to conduct should be minimized, or avoided if possible. “Accelerated testing” is the quixotic answer to this constraint, but the acceleration of the controlling processes must be done with a complete knowledge of how they work and what an appropriate accelerating ","PeriodicalId":104058,"journal":{"name":"Composites and Functionally Graded Materials","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114983351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal Expansion Behavior of Ceramic Composites for Thermal Management Applications","authors":"Yu‐Lin Shen","doi":"10.1115/imece1997-0689","DOIUrl":"https://doi.org/10.1115/imece1997-0689","url":null,"abstract":"\u0000 The thermal expansion response of ceramic composites containing a metallic phase for thermal management applications is studied. The two types of composites considered include a SiC particulate/Al composite (with a large extent of particle contact due to high SiC content) and a SiC/Al interpenetrating composite. Numerical modeling using the finite element method is carried out to provide insights into the experimentally measured deformation behavior. It is found that processing induced residual porosity at the particle contact areas and the sharp concave comers of SiC can govern to a significant degree the thermal expansion response of the composites. The micromechanisms responsible for such effects are identified.","PeriodicalId":104058,"journal":{"name":"Composites and Functionally Graded Materials","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132941335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}