Volume 9: Mechanics of Solids, Structures, and Fluids最新文献

{"title":"Guidelines and Limitations of the Compact Compression Specimen","authors":"David J. Plechaty, K. Carpenter, J. Parmigiani","doi":"10.1115/imece2019-11713","DOIUrl":"https://doi.org/10.1115/imece2019-11713","url":null,"abstract":"\u0000 Damage initiation and propagation material models for carbon fiber composites can be categorized according to the loading applied to constituent components. An example of such categorization is fiber tension, fiber compression, matrix tension, and matrix compression material models. Of these, matrix compression has been by far the least studied based on amount of published literature. Recent work at Oregon State University (OSU) has begun to address this lack of study. OSU researchers have published several papers culminating in the specification of an effective test specimen for isolating matrix compression damage initiation and propagation in carbon fiber laminates. While providing compelling results indicating the effectiveness and usefulness of this test specimen, little or no information has been provided regarding its manufacture, usable notch lengths, and optimum loading rate during testing. Experience at OSU has shown that this information is critical and not trivial to obtain. The purpose of this paper is to provide specific guidelines and “lessons learned” needed for other researchers to efficiently and effectively use this specimen in a comprehensive study. Test specimens are manufactured in the OSU Composites Materials Manufacturing Laboratory using typical commercial pre-peg carbon fiber following the specified layup and curing procedures. Once the material was cured the carbon fiber plate was then water-jet cut into the desired geometry and notch length. Usable notch length and optimum loading rate was determined by testing a series of specimens. All testing was conducted at an OSU lab using a universal testing machine with Digital Image Correlation (DIC) data collected. Specimens were preloaded and matrix compression initiation and propagation data collected until tensile failure occurred on the back edge of the specimen. Testing showed that shorter notch lengths result in inconsistent data and longer in effective initiation but limited propagation due to reduced ligament length. Testing suggested that a speed less than 5 mm/min gave the best results as faster displacement rates caused less crack propagation to occur, while increasing the likelihood of the specimen to fail in tension along its back edge. Through the use of these guidelines, researchers are able to manufacture and use an effective test specimen for the investigation of matrix compression damage initiation and propagation.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114663320","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":"Electro-Mechanical Behavior of Smart Sandwich Plates With Porous Core and Graphene-Reinforced Nanocomposite Layers","authors":"K. Behdinan, R. Moradi‐Dastjerdi","doi":"10.1115/imece2019-10796","DOIUrl":"https://doi.org/10.1115/imece2019-10796","url":null,"abstract":"\u0000 The use of piezoelectric sensor and/or actuator layers in engineering structures provides smart sandwich structures with adaptive responses. Moreover, due to the brittle behavior of piezoceramic materials, inserting nanocomposite and porous layers between piezoelectric layers offers more flexible and lighter structures along with maintaining the advantages of nanocomposite materials. Therefore, in this paper, we have proposed smart sandwich plates consisting of a porous polymeric core and two graphene-reinforced composite (GRC) layers integrated with two piezoceramic layers. The distributions of porosities and randomly oriented graphene particles are assumed to be functionally graded (FG) along the thickness of core and nanocomposite layers, respectively. For the static behavior of the proposed sandwich plates, the coupled electro-mechanical governing equation has been extracted by minimizing potential energy equation with respect to displacement and electrical potential. The governing equation has been discretized by adopting a higher order shear deformation theory (HSDT) of plates and a developed mesh-free method. Using the developed solution framework, the effects of porosity and graphene characteristics, electromechanical loads, and layer thicknesses on the deflection behavior of the proposed FG piezoelectric porous nanocomposite sandwich plates (FG-PPNSPs) have been studied.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"45 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120900644","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":"Experiments on Vortex Shedding From Reconfigured Flexible Filaments Vibrating in Flow","authors":"Jorge Silva-Leon, A. Cioncolini","doi":"10.1115/imece2019-10393","DOIUrl":"https://doi.org/10.1115/imece2019-10393","url":null,"abstract":"\u0000 This paper describes an experimental study of the spanwise vortex shedding frequencies from cantilever flexible filaments which are bent (reconfigured) when exposed to air crossflow. At a reduced velocity of approximately U* = 1500 (based on filament diameter) the filaments started to vibrate in the inline direction. Hot-wire anemometry was thus employed to investigate the wake flow of filaments of three aspect ratios (L/D = 38, 80, and 113) at Reynolds numbers Re < 300. Despite the large relative inclination angles between the filament and the flow direction, the vortex shedding frequency measured along the span of the filaments remained close to those of a cylinder in pure crossflow. Moreover, it was found that as the aspect ratio (axial length) of the filaments was increased, vortex shedding lost coherence towards the free end of the filaments, whereas this was not the case for the shortest aspect ratio filament currently tested. This is thought to be due to the interaction between the crossflow vortex shedding and the axial flow component developing along the wake of the inclined filaments. Through comparisons with stiff inclined wires it was confirmed that the spanwise vortex shedding behaviors observed (frequency and coherence) were not modulated by the motions of the filaments.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124555070","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 the Creep Damage of P91 Steel Using Peridynamics","authors":"S. Kulkarni, A. Tabarraei, Xiaonan Wang","doi":"10.1115/imece2019-10069","DOIUrl":"https://doi.org/10.1115/imece2019-10069","url":null,"abstract":"\u0000 Creep is an important failure mechanism of metal components working at a high temperature. To ensure the structural integrity and safety of systems working at high temperature it is essential to predict failure due to creep. Classical continuum based damage models are used widely for modeling creep damage. A more recently developed non-local mechanics formulation called peridynamics has displayed better performance in modeling damage with respect to classical local mechanics methods. In this paper, the peridynamic formulation is extended to model creep in metals. We have chosen Liu-Murakami creep model for developing a peridynamic formulation for modeling creep. The proposed formulation is validated by simulating creep tests for P91 steel and comparing the results with experimental data from the literature.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128137724","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":"Monotonic and Fatigue Testing of Polymer and Composite Materials Used in Heavy Duty Trucks","authors":"Kevan W. F. Gahan, J. Parmigiani","doi":"10.1115/imece2019-11680","DOIUrl":"https://doi.org/10.1115/imece2019-11680","url":null,"abstract":"\u0000 Improved material models for engineered polymer and composite materials including both monotonic and fatigue characteristics are necessary for creating more accurate digital simulations for heavy duty trucks. Unlike steel and other alloys that are commonly included in truck designs, these advanced polymer materials do not have pre-existing fatigue characteristic data. Additionally, there are no individual standard test procedures that can be commonly cited and followed during a research program. These materials are found in hoods, dashboards, body panels and splash shields of trucks, and are subject to cyclic loading conditions at various amplitudes and durations throughout the entire use or “duty cycle” of the vehicle. The applied loads vary between truck models, as some trucks will be used for vocational purposes and others will remain on the highway. This paper describes the testing of isotropic non-reinforced, and anisotropic glass-fiber-reinforced polymers and the subsequent calculation of the monotonic and fatigue properties that are needed to describe their behavior under various loading conditions. Material characteristics are measured using a series of constant amplitude strain-controlled fatigue tests that follow standard practices from ASTM D638 (Standard Test Method for Tensile Properties of Plastics), ASTM E606 (Standard Practice for Strain-Controlled Fatigue Testing) methods, and SAE J1099 (Technical Report on Low Cycle Fatigue Properties of Ferrous and Non-Ferrous Materials). The ASTM D638 Type 1 coupon geometry is used for all materials, with a varied sample thickness and length. An axial extensometer is incorporated to measure strain data through the duration of all tests, and an anti-buckling fixture is installed during cyclic tests to eliminate any bending in the specimen during the compressive portion of the fully-reversed waveform. A transverse extensometer is also installed on the gauge length of the material coupons to measure instantaneous cross-sectional area as well as Poisson’s ratio during monotonic testing. The data collected through the monotonic testing procedure is used to calculate Young’s Modulus, Poisson’s ratio, ultimate tensile strength, elongation (% strain), yield strength and strain, and true fracture strength and strain. The fatigue testing procedure yields data that can be used to calculate the fatigue strength coefficient (σf′), fatigue strength exponent (b), fatigue ductility coefficient (εf′), and fatigue ductility exponent (c). These parameters provide accurate stress-strain, cyclic stress-strain, and strain-life curves for the materials in question. A method will also be suggested for calculating the stress-life fatigue parameters, stress range intercept and slope, from the strain-controlled data. Furthermore, mold-flow analysis is applied to predict general orientation of the reinforcement fibers induced by the direction of material flow as a part is injection-molded. The calculated monotonic and ","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129047312","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":"Defect Induced Variabilities in Thermal Conductivity of Nano Structures","authors":"Sushan Nakarmi, V. Unnikrishnan","doi":"10.1115/imece2019-11654","DOIUrl":"https://doi.org/10.1115/imece2019-11654","url":null,"abstract":"\u0000 The high thermal conductivity of carbon nanotubes makes them ideal candidates for use as nano-fins for thermal management in electronics and composites. At the nanoscale, the thermal conductivity of nanotubes are found to be dependent on size, strain states, temperature, and presence of defects and vacancy. The proper understanding of the effect of these parameters are important in constructing a nanotube system with desired thermal characteristics. Here, we pay special focus on the effect of different kinds of defects and vacancies on the thermal conductivities of nanotubes. Defects and vacancies are imperfections in an otherwise hexagonal structure of nanotube. Their presence have shown to impede the thermal transport in nano-structures which is attributed to the scattering of phonons that occurs in these imperfections. The thermal conductivities of (10,10) armchair nanotube with defects and vacancies are determined using the heat bath method, a non-equilibrium molecular dynamic simulation and are compared with that of pristine carbon nano-structures. This is followed by the comparative study of phonon density of states of nanotubes with and without the defects.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132506465","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":"Composite Fabric Blankets for Plastic Gears","authors":"S. Kini, A. F. Aznar, H. Ghoneim","doi":"10.1115/IMECE2018-86074","DOIUrl":"https://doi.org/10.1115/IMECE2018-86074","url":null,"abstract":"Two approaches for increasing the load capacity of plastic gears in general are proposed and investigated: modifying the conventional involute profile of the gear tooth surfaces by applying a parabolic-crowned profile, and introducing a composite fabric, which blankets the surface of the teeth. The investigation is carried out using the finite element method (IGD/ANSYS). A five-tooth model is applied for the gears, and nylon and carbon/nylon are adopted for the materials. The evolution of maximum contact and bending stresses is evaluated over two cycles of meshing for both the pure plastic (nylon) gears and the gears with the composite surface blanket (carbon/nylon) to investigate the process of transfer of load between consecutive pairs of teeth and detect possible edge contacts. The results indicate that selecting the proper parabolic-crowned profile helps to alleviate the contact stress, and more specifically, to reduce the peaks of contact stresses due to edge contacts at the tip of the teeth. The results also indicate that there are an optimum parabolic-crowned profile and an optimum thickness of the composite blanket, which render the lowest maximum level of contact stresses over the cycle of meshing and bending stresses at the fillet. However, this preliminary research work suggests that, for the case considered, the novel idea of composite blanket is inconclusive — though the blanket may protect the plastic core, it itself becomes vulnerable to failure. The idea is being explored more, and the results will be disseminated in a future work.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114779012","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":"An Integrated Approach for Statistical Microscale Homogenization to Macroscopic Dynamic Fracture Analysis","authors":"B. Bahmani, Ming Yang, Anand Nagarajan, P. Clarke, Soheil Soghrati, R. Abedi","doi":"10.1115/IMECE2018-88429","DOIUrl":"https://doi.org/10.1115/IMECE2018-88429","url":null,"abstract":"Maintaining material inhomogeneity and sample-to-sample variations is crucial in fracture analysis, particularly for quasibrittle materials. We use statistical volume elements (SVEs) to homogenize elastic and fracture properties of ZrB2-SiC, a two-phase composite often used for thermal coating. At the mesoscale, a 2D finite element mesh is generated from the microstructure using the Conforming to Interface Structured Adaptive Mesh Refinement (CISAMR), which is a non-iterative algorithm that tracks material interfaces and yields high-quality conforming meshes with adaptive operations. Analyzing the finite element results of the SVEs under three traction loadings, elastic and angle-dependent fracture strengths of SVEs are derived. The results demonstrate the statistical variation and the size effect behavior for elastic bulk modulus and fracture strengths. The homogenized fields are mapped to macroscopic material property fields that are used for fracture simulation of the reconstructed domain under a uniaxial tensile loading by the asynchronous Spacetime Discontinuous Galerkin (aSDG) method.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131617336","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":"A Generalized Approach to Improve Approximation of Inverse Langevin Function","authors":"V. Morovati, H. Mohammadi, R. Dargazany","doi":"10.1115/IMECE2018-88228","DOIUrl":"https://doi.org/10.1115/IMECE2018-88228","url":null,"abstract":"The inverse Langevin function has a crucial role in different research fields, such as polymer physics, para- or superpara-magnetism materials, molecular dynamics simulations, turbulence modeling, and solar energy conversion. The inverse Langevin function cannot be explicitly derived and thus, its inverse function is usually approximated using rational functions. Here, a generalized approach is proposed that can provide multiple approximation functions with a different degree of complexity/accuracy for the inverse Langevin function. While some special cases of our approach have already been proposed as approximation function, a generic approach to provide a family of solutions to a wide range of accuracy/complexity trade-off problems has not been available so far. By coupling a recurrent procedure with current estimation functions, a hybrid function with adjustable accuracy and complexity is developed. Four different estimation families based four estimation functions are presented here and their relative error is calculated with respect to the exact inverse Langevin function. The level of error for these simple and easy-to-use formulas can be reduced as low as 0.1%.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"12 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132968653","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":"Comparison of Interfacial and Continuum Models for Dynamic Fragmentation Analysis","authors":"B. Bahmani, P. Clarke, R. Abedi","doi":"10.1115/IMECE2018-88294","DOIUrl":"https://doi.org/10.1115/IMECE2018-88294","url":null,"abstract":"The microstructural design has an essential effect on the fracture response of brittle materials. We present a stochastic bulk damage formulation to model dynamic brittle fracture. This model is compared with a similar interfacial model for homogeneous and heterogeneous materials. The damage models are rate-dependent, and the corresponding damage evolution includes delay effects. The delay effect provides mesh objectivity with much less computational efforts. A stochastic field is defined for material cohesion and fracture strength to involve microstructure effects in the proposed formulations. The statistical fields are constructed through the Karhunen-Loeve (KL) method. An advanced asynchronous Spacetime Discontinuous Galerkin (aSDG) method is used to discretize the final system of coupled equations. Application of the presented formulation is shown through dynamic fracture simulation of rock under a uniaxial compressive load. The final results show that a stochastic bulk damage model produces more realistic results in comparison with a homogenizes model.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130045703","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}