Journal of Composites Technology & Research最新文献

{"title":"Tensile Stiffness and Strength of Regular Braid Composites: Correlation of Theory with Experiments","authors":"Zheng-ming Huang, K. Fujihara, S. Ramakrishna","doi":"10.1520/CTR11005J","DOIUrl":"https://doi.org/10.1520/CTR11005J","url":null,"abstract":"This paper investigates the tensile behavior of plain regular braided fabric reinforced composites subjected to uniaxial load. An experimental program is performed to characterize the stiffnesses and strengths of a number of braid composites. Two different material systems, i.e., carbon/epoxy and glass/epoxy, were investigated in this study, each with three different braiding angles. A theoretical approach, based on a bridging micromechanics model, is employed to predict the tensile properties of the braid composites only using monolithic fiber and matrix properties and the fabric geometric information as input parameters. These parameters are easily obtainable before or after composite fabrication, and determination of them is described in the paper. Unit cell geometry of the braided fabric in the composite was represented by either elliptic or sinusoidal cross section combined with the same undulation function, and a comparative study has been performed. After the unit cell of the braid composite has been divided into slices and the bridging model has been applied, an assemblage based on iso-stress or iso-strain assumption was adopted to obtain the overall properties of the composite. Although both the assumptions give reasonable predictions for the stiffness of glass/epoxy braid composites, significant differences exist between the predictions from the iso-stress approach and those from the iso-strain approach for the strength of the glass/epoxy composites and for the stiffness and strength of the carbon/epoxy composites. The iso-strain approach combined with the elliptic geometric description exhibits the best accuracy, and the predicted stiffnesses and strengths for the two material systems thus obtained are all within 13% discrepancy with the experimental data.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"100 1","pages":"9388"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73619472","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":"Analysis of Flexure Tests for Transverse Tensile Strength Characterization of Unidirectional Composites","authors":"T. O'Brien, R. Krueger","doi":"10.1520/CTR11004J","DOIUrl":"https://doi.org/10.1520/CTR11004J","url":null,"abstract":"Finite element (FE) analyses were performed on 3-point and 4-point bending test configurations of glass-epoxy and carbon-epoxy unidirectional tape beams tested at ninety degrees to the fiber direction to identify deviations from beam theory predictions. Both linear and geometric non-linear analyses were performed using the ABAQUS® finite element code. The 3-point and 4-point bending specimens were first modeled with two-dimensional elements. Three-dimensional finite element models were then performed for selected 4-point bending configurations to study the stress distribution across the width of the specimens. For 3-point bend test configurations, both the linear and geometric non-linear 2D plane-strain and plane-stress analyses yielded similar results. The maximum tensile stresses under the center load nose calculated from the FE analysis were slightly lower than stresses predicted by beam theory. The difference (maximum of 4%) was greatest for the shortest span analyzed. For 4-point bend test configurations, both the plane-stress and plane-strain 2D linear analysis results agreed closely with beam theory except right below the load points. However, 2D geometric non-linear analyses deviated slightly from beam theory throughout the inner span as well as below the load points. Plane-stress results deviated from beam theory more than plane-strain results. The maximum tensile stresses between the inner span load points were slightly greater than the beam theory result. This difference was greatest (maximum of 4%) for configurations with the shortest spans between inner and outer load points. A contact analysis was also performed in order to investigate the influence of modeling the roller versus modeling the support as a simple boundary condition at one nodal point. The discrepancy between the FE and beam theory results became smaller (max. 2–3%) when the rollers were modeled in conjunction with contact analysis. Hence, the beam theory yields a reasonably accurate value for the maximum tensile stress in bending compared to 2D FE analysis. The FE results are primarily for guidance in the choice of beam thickness, width, and configuration. For the 3-point bend configuration, longer spans are preferred to minimize the error in beam theory data reduction. Similarly, for the 4-point bend configurations, a longer span between the inner and outer load noses, at least equal to the span between the inner load noses, results in less error compared to beam theory. In addition, these FE results indicate that the span between the inner load noses should not be too long to avoid obtaining a non-uniform maximum stress between the inner load noses. Finally, the 3D analysis indicates that specimens should be sufficiently wide to achieve a fully constrained state of plane-strain at the center of the specimen width.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"107 1","pages":"1-19"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86972126","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":"Influence of Specimen Configuration and Size On Composite Transverse Tensile Strength and Scatter Measured Through Flexure Testing","authors":"T. O'Brien, A. Chawan, Kevin R. DeMarco, I. Paris","doi":"10.1520/CTR11003J","DOIUrl":"https://doi.org/10.1520/CTR11003J","url":null,"abstract":"The influence of specimen configuration and size on the transverse tensile strength of two glass/epoxy materials, and one carbon/epoxy material, loaded in three and four-point bending was evaluated. Transverse tensile strength was typically lower for longer span lengths due to the classical weakest link effect. However, strength was less sensitive to volume changes achieved by increasing specimen width. The Weibull scaling law typically over-predicted changes in transverse tensile strengths in three-point bend tests and under-predicted changes in transverse tensile strengths in four-point bend tests. Furthermore, the Weibull slope varied with specimen configuration, volume, and sample size. Hence, this scaling law was not adequate for predicting transverse tensile strength of heterogeneous, fiber-reinforced, polymer matrix composites.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"51 1","pages":"1-19"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86769949","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":"End-Notched Flexure Testing and Analysis of Mode II Interlaminar Fracture Behavior of Glass-Cloth/Epoxy Laminates at Cryogenic Temperatures","authors":"K. Horiguchi, Y. Shindo, Hiroyuki Kudo, S. Kumagai","doi":"10.1520/CTR10930J","DOIUrl":"https://doi.org/10.1520/CTR10930J","url":null,"abstract":"This paper presents results from an analytical and experimental study of the effect of temperature and geometrical variations on the Mode II interlaminar fracture toughness in glass-cloth/epoxy laminates. The end-notched flexure (ENF) test geometry was used for Mode II experiments, which were performed at room temperature (R.T.), liquid nitrogen temperature (77 K), and liquid helium temperature (4 K). The fracture surfaces were also examined by scanning electron microscopy to verify the fracture mechanisms. A finite element model was further used to perform the delamination crack analysis. Critical load levels, and the geometric and material properties of the test specimens were input data for the analysis, which evaluated the Mode II energy release rate at onset of delamination crack propagation. The results of the finite element analysis are used to supplement the experimental data.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"71 1","pages":"239-245"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81655777","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 Material Heterogeneity on the Shock Response of Layered Systems in Plate Impact Tests","authors":"N. Chandra, Xianglei Chen, A. Rajendran","doi":"10.1520/CTR10929J","DOIUrl":"https://doi.org/10.1520/CTR10929J","url":null,"abstract":"In the study of shock wave propagation in solids, scattering, dispersion, and attenuation play a critical role in determining the thermomechanical response of the media. These phenomena can be attributed to a number of nonlinearities arising from the wave characteristics, loading conditions, material heterogeneity (measured at various spatial scales ranging from nanometers to a few millimeters). The nonlinear effects in general can be ascribed to impedance (and geometric) mismatch present at various length scales as often encountered in composite material systems, apart from material nonlinearities arising from inelastic effects, void nucleation and growth, cracking, and delamination. However, in nearly brittle material systems, elastic effects dominate and is the only effect considered here. Uniaxial strain experiments on the S-2 glass/polymer composite system display markedly different behavior than that observed in monolithic metallic systems [6] and this motivated the present work. Stress profiles measured at various locations along the direction of wave propagation in the plate impact experiments showed that the shock wave rise time increased with propagation in addition to the reduction of peak stress. In this work, we specifically address the issue of shock wave rise time in a simplified multi-layered system. A careful analysis of wave propagation in heterogeneous medium is performed by considering the elastic/acoustic properties of individual lamina in a layered system. An analytical model has been developed to describe the scattering process (reflection/transmission) at various layer interfaces of multilayer composite system. FEM results are then used to compare with the analytical predictions. These results show that the rise time can be a consequence of multiple internal reflections and transmissions occurring at the heterogeneous interfaces, it is further shown that the rise time depends on the magnitude of impedance mismatch and the number of layers.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"38 1","pages":"232-238"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76906690","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":"Adhesion of Stainless Steel to Fiber Reinforced Vinyl Ester Composite","authors":"Joseph D. Melograna, J. Grenestedt","doi":"10.1520/CTR10932J","DOIUrl":"https://doi.org/10.1520/CTR10932J","url":null,"abstract":"Joints between stainless steel and composites have many applications. For example, marine vessels may be composed of a steel hull joined to a composite bow, stern, and/or topside structure. Joining these components adhesively is a major structural challenge, and overcoming this challenge necessitates the development of strong adhesion between steel and composites. The present study investigates AL-6XN stainless steel and glass fiber reinforced vinyl ester. Several specimens were manufactured with different surface preparations, adhesives, and/or additives. Short-term transverse tensile strength in dry conditions was used as the measure by which the different strategies were compared. All specimens were manufactured using a vacuum infusion technique, with the steel embedded within the fiber reinforcements before the molding. No secondary bonding was done.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"289 1","pages":"254-260"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83143215","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":"Deflection measurements of laminated thin plates using Electronic speckle Pattern interferometry","authors":"D. Golda, D. Kedlaya, A. Pelegri","doi":"10.1520/CTR10927J","DOIUrl":"https://doi.org/10.1520/CTR10927J","url":null,"abstract":"An adaptive Electronic speckle Pattern Interferometry (ESPI) system has been developed to measure out-of-plane de formation of laminates subjected to quasi-static loads. The systeir was installed and setup for calibration with aluminum specimens mounted to an optical breadboard. Several parameters of the test fixture and system's geometry needed to be adjusted before usable fringe patterns were obtained, and the system's resolution and range were determined. The ESPI system was then reconfigured for use with composite specimens subjected to quasi-static loading. Results of fringe patterns, calibration curves and deformation patterns are presented for Al and graphitelepoxy specimens. The ESPI resolution was estimated at 25 μm per fringe for the Al surface, and 11 μm per fringe for the composite laminate. From the results, it can be concluded that the usable deflection range is limited at high systeir resolutions.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"9 1","pages":"215-223"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84789316","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 Statistical Approach for Optimizing the Fracture Toughness of a Composite Laminate","authors":"A. Tekkam, A. Pelegri","doi":"10.1520/CTR10928J","DOIUrl":"https://doi.org/10.1520/CTR10928J","url":null,"abstract":"Delamination is one of the most critical failure modes in laminated composite structures due to its abrupt and damaging character. In the present investigation a methodology is developed using Designed Experiments and Taguchi concepts to analyze the contribution and significance of several factors to the mode I delamination fracture toughness of a composite structure. The factors tested were selected based on their degree of influence on the fracture toughness and their tailoring adjustability. Considering these two criteria, the most important factors in optimizing a laminate's strength include crack (delamination) length, stacking sequence, width, thickness, and length of the structure. Most importantly, the effect of their first order interactions, i.e., concurrent effect, on a damaged laminate is investigated. All the factors are regarded at two levels and a Fractional Factorial experiment is conducted. Taguchi arrays are used to select the combination of factors that will maximize the amount of information from the minimum number of experiments. The idea of significant factors and their interactions is then used to obtain a response surface equation. Estimation of the structure's interlaminar fracture toughness follows once the response surface equation is identified. The developed methodology significantly reduces the required number of experiments and qualitatively describes the effect of various factors, and their interactions, on the fracture toughness. Experimental and analytical results, employing the optimal combination of factors as determined by the presented method, are in good agreement.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"8 1","pages":"224-231"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74240636","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":"Fiber dominant tensile and creep strength at 600°C of SCS-6 fiber reinforced titanium alloys","authors":"P. Peters, J. Hemptenmacher, K. Weber, H. Assler","doi":"10.1520/CTR10931J","DOIUrl":"https://doi.org/10.1520/CTR10931J","url":null,"abstract":"The influence of the fiber strength on the unidirectional tensile and creep strength at 600°C has been investigated. Single fiber tensile tests are performed at 600°C and the resulting Weibull strength distribution is compared with the room temperature distribution. The 600°C characteristic strength is found to be only 7.6% smaller than that at room temperature. Fibers extracted from loaded-unloaded specimens at 600°C show more failures than expected on the basis of the 600°C Weibull strength distribution determined as manufactured fibers. From this and other experiments it is concluded, that the in-situ tensile strength of fibers at 600°C (embedded in the titanium) is smaller than that of manufactured fibers. Relaxation behavior of the unreinforced titanium alloys was investigated and described with the aid of Bailey-Norton creep law. This enables description of the stress redistribution during creep of the unidirectional composites performed in short time creep experiments up to ∼100 h. The creep strength has been described considering stress relaxation in the matrix and slow defect growth in the fibers. From the shape of the creep strength-life curve it is concluded that three different ranges of defect growth contribute to the creep strength.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"6 1","pages":"246-253"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75786915","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":"Efficient Adaptive Mesh Refinement Modeling of Adhesive Joints","authors":"A. Tessler, M. Dambach, D. Oplinger","doi":"10.1520/CTR10567J","DOIUrl":"https://doi.org/10.1520/CTR10567J","url":null,"abstract":"The smoothing element analysis for stress recovery and error estimation is applied to facilitate adaptive finite element solutions of adhesively bonded structures. The formulation is based on the minimization of a penalized discrete least-squares variational principle leading up to the recovery of C 1 -continuous stress fields from discrete, Gauss-point finite element stresses. The smoothed distributions are then used as reference solutions in a posteriors error estimators. Adaptive mesh refinements are performed to predict the linearly elastic response of uniformed and tapered double splice adhesively bonded joints. Key aspects pertaining to specific smoothing strategies, adaptive refinement solutions, and detailed stress distributions are discussed. Consistent comparisons are also presented with Oplinger's one-dimensional adhesive lap joint analysis.","PeriodicalId":15514,"journal":{"name":"Journal of Composites Technology & Research","volume":"605 1","pages":"152-179"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76796189","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}