Recent Advances in Solids and Structures最新文献

{"title":"Probabilistic HCF Life Estimation of a Mechanical Component","authors":"Murari P. Singh","doi":"10.1115/imece2001/pvp-25211","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25211","url":null,"abstract":"\u0000 Goodman Diagram method or similar methods are used to estimate safety of a mechanical structure under high cycle fatigue loading for any combination of alternating and mean stresses. Magnitude of the factor of safety (FS) indicates margin from nominal design capable of desired performance. The value of larger than one of FS is desired to account for uncertainty and variability in loads and material properties. This FS based on stress does not provide any direct knowledge about the life of the mechanical structure. A FS based on life can be derived and used in conjunction with Goodman concept. This method yields an estimate of FS based on life (FN) for a given stress based FS for any combination of alternating and mean stresses.\u0000 A procedure is described in this paper that helps in estimating reliability of a mechanical structure. Reliability depends on the magnitude of stresses and material properties. Usually variability in load and in material properties can be quantified by a statistical distribution. Methods of probabilistic theories can be used to determine the influence of these variations on the reliability.\u0000 The procedure utilizes established methods and theories to yield practical evaluation of reliability. First, the modified Goodman equation of factor of safety is combined with the life equation proposed by Jo Dean Morrow (Dowling, 1999). This provides a relationship between calculated factor of safeties based on stress and life. Finally, the developed equations are utilized in a probabilistic approach that incorporates statistical distribution of uncertainties. This procedure yields reliability assessment of a mechanical structure to perform an expected task.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127866792","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":"Semi-Analytical Modeling of Progressive Damage in Twill Woven Textile Composites","authors":"P. Chaphalkar, Ajit O. Kelkar","doi":"10.1115/imece2001/pvp-25212","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25212","url":null,"abstract":"\u0000 Various alternative composite materials like, textile composites, especially woven, are being developed and tried in place of conventional multidirectional laminates, because they have better properties in mutually orthogonal directions and out of plane properties than the multidirectional laminates. In structural applications, predictions of the elastic modulii, Poisson’s ratios from the weave architecture and the properties of the constituents are required. There are various parameters that characterize the weave architecture of woven laminate composites. In repeated loading, the matrix cracking occurs, degrading matrix properties. This in turn degrades the effective properties of the woven composites. Analytical models are necessary to study the effects of these parameters on the behavior of woven fabric composites and to design efficient woven structure for particular application. The objective of the current paper is to study the effect of matrix cracking on the effective properties of the twill woven composites by degrading the matrix properties. First the effective properties of the composite material, without any matrix cracks, are determined by using an analytical model, which predicts the stiffness of the twill woven composites. This model takes into account effects of the actual fabric structure with various tow cross sections by considering tow undulations and continuity along both the fill and warp directions.\u0000 In twill woven composites, there is a weaker matrix along with the stronger medium i.e. the glass fibers. The matrix first fails and then the load is transferred to the fibers. The matrix properties are degraded in the resin pockets and also in the transverse tows only. This is because normally matrix cracking first occurs in the transverse tows (cracks originate in the tows that run in the transverse direction to the loading). The degradation of the properties includes the Young’s Modulus and the Poisson’s ratio of the resin. With these modified properties of the resin, the homogeneous properties of the transverse tows are calculated. At each degradation step the effective properties of the composite material are evaluated. This progressive failure is continued till the matrix loses most of its strength.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121623173","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":"Material Considerations in Optimization of Machine Tool Structure","authors":"E. Kushnir, M. R. Patel, T. Sheehan","doi":"10.1115/imece2001/pvp-25216","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25216","url":null,"abstract":"\u0000 The three most popular choices currently used for the main structural components of machine tools are steel weldments, metal (cast iron) castings and polymer composites. Among the three, polymer composite offers the highest vibration damping and the lowest thermal conductivity. All three approaches have been employed in the design of machine tools to meet the criteria for required rigidity, impact resistance and vibration damping. The final choice is also affected by additional factors including cost footprint (space) requirements and lead times.\u0000 For most production applications of machine tool structures, (gray cast iron) metal castings remain the primary choice because of cost, ease of sourcing, good damping with relatively high strength, good machinability and well-established and consistently achievable manufacturing and processing requirements. However, fabrications are normally the preferred choice for low volume production of large structures, due mainly to the high up-front molding costs and the difficulties in process control inherent in very large castings. On the other hand, with increasing, emphasis on high speed machining, hard turning, and better and consistent machining accuracies, structural rigidity, thermal stability and vibration damping are becoming major design considerations making polymer composites a leading choice.\u0000 For this reason, Hardinge Inc., a super precision machine tool builder has traditionally used its proprietary polymer composite (Harcrete®) in its lathe, grinder and machining center bases. Depending on the performance and cost requirements, the base can be all composite or a combination of conventional casting strategically reinforced with composite.\u0000 With the current market forces and ever increasing competition in the industry, for most machines, value engineering has become a prominent factor. A major consideration is to identify the materials and designs that would provide the best performance of the machine while minimizing the cost. Therefore, new sets of evaluation criteria are necessary to arrive at designs with optimum cumulative impact on various technical, commercial and strategic requirements. This paper proposes such new criteria and examines their suitability based on testing and analyses of structural components in today’s demanding real-world machine tool applications.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133397973","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":"Corrosion Resistance of Structural Steel Processed Using Electro-Plasma Methods","authors":"P. Schilling, P. Herrington","doi":"10.1115/imece2001/pvp-25215","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25215","url":null,"abstract":"\u0000 Electro-plasma cleaning and deposition is a recently developed electrolytic method for cleaning mill scale and other debris from steel surfaces, and depositing protective metal coatings. Structural steel was processed using these methods and tested for corrosion resistance. Samples included freshly cleaned steel coupons and samples coated with a metallic zinc layer. Tests included linear polarization resistance, QUV weathering, salt fog exposure, and electrochemical impedance spectroscopy. Steel samples cleaned by electro-plasma methods exhibited superior corrosion resistance to those cleaned by shot-blasting. The zinc metal coatings demonstrated potential for long-term corrosion protection.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133338184","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":"Laying Modeling of Submarine Pipelines Using Contact Elements Into a Corotational Formulation","authors":"Cora E. Martínez, Raúl Goncalves","doi":"10.1115/1.1555117","DOIUrl":"https://doi.org/10.1115/1.1555117","url":null,"abstract":"\u0000 A new finite element formulation to analyze stresses and displacements in submarine pipelines during laying operations is presented in this paper. The method is based on the corotational formulation using Bernoulli non-linear beam elements to model the large displacements and rotations of the pipeline. The penalty method is used with spring-contact elements to accurately represent the actual boundary conditions. During the lay barge installation, the pipe rolls over the barge ramp and slides over the stinger before reaching the sea floor. The barge stinger is a ramp over floating supports that holds the pipeline in such a way that the pipe adopts an S-curve during the laying process. Since contact elements allow the pipeline to separate from the stinger at those points where the contact is lost, introducing these elements into the analysis makes it possible to accurately model the actual boundary conditions on the stinger. In addition, the use of contact elements allows the pipe to reach the sea floor at all those points, which naturally require this condition without imposing any displacement boundary condition during the convergence process. A real laying case of an oil transportation submarine pipeline is presented at the end of the paper to validate the results obtained with the developed formulation. A comparison with a finite element formulation introduced by the authors in a previous paper is also presented in order to verify the accuracy and computational effectiveness of the proposed method.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117290607","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":"Biodynamics of Human Thorax With Body Armors Subject to Bullet Impact","authors":"Y. W. Kwon, J. A. Lobuono","doi":"10.1115/imece2001/pvp-25206","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25206","url":null,"abstract":"\u0000 The objective of this study is to develop a finite element model of the human thorax with a protective body armor system so that the model can adequately determine the thorax’s biodynamical response from a projectile impact. The finite element model of the human thorax consists of the thoracic skeleton, heart, lungs, major arteries, major veins, trachea, and bronchi. The finite element model of the human thorax is validated by comparing the model’s results to experimental data obtained from cadavers wearing a protective body armor system undergoing a projectile impact.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132241370","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":"The Effect of Precipitation Aging on the Mechanical Behavior and Microstructure of Aluminum-Lithium Alloys","authors":"J. Fragomeni","doi":"10.1115/imece2001/pvp-25208","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25208","url":null,"abstract":"\u0000 The effect of variations in microstructure as a consequence of heat treating and aging on the mechanical properties of aluminum-lithium alloys was studied. The thermal treatments and composition were correlated to the microstructure and subsequent mechanical behavior of aluminum-lithium and aluminum-lithium-copper alloys that were solution heat treated and artificially aged for a series of aging times and temperatures. The underaged, peak-aged, and overaged thermal heat treatments were considered in determining the effect of the microstructure and processing on the mechanical properties. Standard ASTM tensile testing of the alloys was performed to determine mechanical properties such as yield strength, ductility, and ultimate tensile strength. Quantitative microscopy of the intermetallic precipitates was performed to related the measured deformation behavior to the microstructural features. Thus, the intermetallic precipitates in the microstructure which impede dislocation motion and control the precipitation strengthening response as a function of aging practice were measured by quantitative methods, and are the basis for controlling the mechanical behavior depending on their size distribution, average size, and interparticle spacing. The microstructure was studied, and measurements were made to determine the size, distribution, and morphology for the intermetallic strengthening precipitates as a function of the processing and composition. For the aluminum-lithium alloys studied, the primary strengthening was a direct consequence of ordered coherent Al3Li intermetallic precipitates which were uniformly distributed throughout the microstructure, which restricted the glide motion of dislocations during plastic deformation.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129826457","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":"Estimating the Initial Crack Size in a Particulate Composite Material: An Analytical and Experimental Approach","authors":"C. Liu","doi":"10.1115/imece2001/pvp-25202","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25202","url":null,"abstract":"\u0000 In this study, a technique to predict the equivalent initial crack size (EICS) in a particulate composite material, containing hard particles embedded in a rubber matrix, was developed using constant strain rate crack propagation test data. The accuracy of the developed technique was determined. In addition, the statistical distribution of the equivalent initial crack size follows the second asymptotic distribution of maximum value.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123737180","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":"Stress Intensity Factors and Paths for Cracks in Photoelastic Motor Grain Models Under Internal Pressure","authors":"C. Smith, D. Constantinescu, C. Liu","doi":"10.1115/imece2001/pvp-25200","DOIUrl":"https://doi.org/10.1115/imece2001/pvp-25200","url":null,"abstract":"\u0000 Computational analysis and two-dimensional tensile tests on single motor grain fins suggest that cracks in fin tips are most likely to originate at the coalescence of a fin end tip radius, with a small radius from the side of the fin. Some manufacturers have also noticed defects formed during casting at the fin tip on the fin axis. The following is an experimental investigation utilizing frozen stress photoelastic models of an existing motor grain geometry in order to clarify stress intensity factor (SIF) values and crack growth paths for cracks emanating from the two above-noted potential critical loci. Comparisons between results from cracks grown from the two loci will be made, suggesting interesting conclusions.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"181 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116279339","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":"Modeling of Hydrostatic Pressure Effect on Progressive Damage in Particulate Composites","authors":"Y. W. Kwon, C. Liu","doi":"10.1115/imece2000-1249","DOIUrl":"https://doi.org/10.1115/imece2000-1249","url":null,"abstract":"\u0000 Hydrostatic pressure affects the damage growth in a particulate composite. As a result, an analytical model was presented to represent the damage growth in a particulate composite under various hydrostatic pressures. The model was based on a multi-level approach with damage description at the micro-level. A damage theory was presented to describe the material behavior under hydrostatic pressure. The predicted stress-strain curves compared well with the experimental measurements. Furthermore, the initial crack size at a notch tip was studied with and without hydrostatic pressure.","PeriodicalId":270413,"journal":{"name":"Recent Advances in Solids and Structures","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124926928","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}