Papers by Keyword: Biaxial Tension

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Authors: Fu Ming Chen, Ge Wang, Ze Hui Jiang, Hai Tao Cheng, Xiao Meng Chen, Zi Xuan Yu, Wen Fu Zhang
Abstract: To evaluate the mechanical properties of natural fiber fabrics with the characteristic of interweaving between warp and weft direction as well as textile structural composites under complex stress state, it is essential to develop experimental techniques to realize multi-axial testing for large deformation. This work proposes a novel testing device for investigating fiber fabrics and textile composites under multidimensional loads. Accuracy of the system is comparable to the testing diagnostics of the Instron 5808 previously. The homogeneity for different types of cruciforms and different biaxial tensile speeds were investigated. The effects of different loading methods, biaxial (X and Y), and 3-D loading (X, Y, and Z) on the breaking strength of the woven ramie fabric were presented. The displacement-field and shear field for composites with hole were characterized by the digital speckle correlation method.
Authors: Wei Wang, Shi Yan, Gang Bing Song, Li Jiao
Abstract: An improved two-dimensional constitutive model for shape memory alloys (SMAs), which can describe both the shape memory effect (SME) and super elasticity effect (SE) of the SMAs, is developed in the paper based on the previous work of Boyd and Lagoudas, who used the thermodynamics theories of free energy and dissipation energy to derive the constitutive law of the SMAs. The improved model, which will combine the ideas of Brinsion’s one-dimensional constitutive law and the concepts of Boyd and Lagoudas’ two-dimensional one, has a simple but accurate expression. Two examples are used to numerically validate the efficiency of the improved model and the results of the simulations show that the developed constitutive model can qualitatively describe the thermo-mechanical behaviors of two-dimensional SMAs.
Authors: Sergey A. Aksenov, Ivan Y. Zakhariev, Aleksey V. Kolesnikov, Sergey A. Osipov
Abstract: Determination of material constants describing its behavior during superplastic gas forming is the main subject of this study. The main feature of free bulging tests is the stress-strain conditions which are very similar to ones occurring in the most of gas forming processes. On the other hand, the interpretation of the results of such tests is a complicated procedure. The paper presents a simple technique for the characterization of materials superplasticity by free bulging tests, which is based on inverse analysis. The main idea of this technique is a semianalytical solution of the direct problem instead of finite element simulation which allows one to reduce the calculation time significantly. At the same time the results this simplified solution are accurate enough to obtain realistic material constants.
Authors: Pierre Ouagne, Damien Soulat, Christophe Tephany, Julien Moothoo, Samir Allaoui, Gilles Hivet, Davy Duriatti
Abstract: A flax fibre plain weave fabric has been used to form a complex tetrahedron shape. The global shape has been obtained. Even if no apparent defects are visible when observing the yarns, the strain of the tightest yarns of the preform has been measured and compared to the biaxial strains of the fabric determined independently of the process. The results show that the strains in the yarns close to the triple point of the shape (top of the tetrahedron) are higher than the strain at failure. This could lead to local lack of fibre density and to possible zones of weakness for the composite part. It is therefore necessary to increase the tensile performances of the yarns constituting the fabric.
Authors: Masafumi Noda, Kunio Funami
Abstract: The grain boundary sliding and the formation of slipped bands and cavitations during biaxial tensile deformation were examined in fine grained Al-Mg alloy. Biaxial tensile testing was conducted with cruciform specimens at initial strain rates of 10-4 to 101s-1. It was found that at the same equivalent strain conditions, the number of cavities under biaxial tension is significantly greater than that under uniaxial tension. A greater prevalence of slipped bands and grain separations were clearly observed under biaxial stress than under uniaxial stress. It was suggested that development of slipped bands resulted from the formation of elongated cavities and multiple deformed bands under biaxial stress. Additionally, the m-value under biaxial stress remained at about 0.3 over a wide range of strain rates. The effects of grain separation and formation of cavities were related to the motion of grain boundary sliding, grain size and loading conditions.
Authors: Akira Shimamoto, Hiroshi Ohkawara, Hong Yang Zhao
Abstract: Stress intensity factor K is analyzed by measuring distribution of sum of the principal stresses around slit tip by an infrared stress measuring device. Under the biaxial tensile stress, both K-values of the isotropic materials with slit angle 0° and 45° show there is no influence of the slit angle at Mode I. The tolerance of the measured K-values of the test specimens which are compared with measured K-values by photoelastic method are around 10-20and these increase as applied cyclic load increases. These tolerance can be reduced up to about 8% by modifying measurements. The effectiveness of the thermoelastic stress measurement method to KI value analyzing under biaxial tensile stress was confirmed.
Authors: Rong Ping Cao, Hong Lei Yi
Abstract: The finite element analysis (FEA) has been widely used in research and production. It is well known that ABAQUS software is famous for its capacity of solving nonlinear problems. Create the test specimen model that is based on biaxial cross tensile test specimen of woven architectural membrane material by the ABAQUS software. The effects of the fillet radius(R), the width of the specimen (W), the length (L) and the number (N) of the crack are considered. It is found that while the whole specimen is 180*180mm it is most uniform when the R is 5mm, the W is 60mm, the L is about 60mm and the N is 5.
Authors: Yi Wang Bao, Rolf W. Steinbrech
Authors: Ge Wang, Fu Ming Chen, Hai Tao Cheng, Zi Xuan Yu, Ze Hui Jiang, Xiao Meng Chen, Wen Fu Zhang
Abstract: The objective of this work was to use a novel 3-D test analysis system for evaluating the mechanical properties of the natural fiber fabric composites under biaxial loads. Composites with three resin matrices (water-based epoxy resin, isocyanate resin, phenolic resin) were investigated, and strain filed were characterized by using the digital speckle correlation. The water-based epoxy resin plate and isocyanate resin plate demonstrated a characteristic of orthotropy and elastoplasticity, while the phenolic resin board revealed linear elastic and brittle-fracture simultaneously at X,Y-axial. Dissimilarities of biaxial load value were related to the orthotropy of composite structure, and load changes in fracture direction had a negative effect on the other directions at breaking moment. The degrees of dropping presented a positive correlation with the load values at rift direction. Under the linear elastic stage, the value of load and average strain at Y-direction were larger than that under X-direction within the same testing area. The strain-filed at X/Y-direction provided by isocyanate and phenolic resin plates illustrated a more smooth change than that of the water-based epoxy resin plate.
Authors: Wei Feng Bai, Jun Hong Zhang, Jun Feng Guan, Ying Cui
Abstract: Based on the statistical damage theory and the experimental phenomena, the statistical damage constitutive model for concrete under biaxial tension is proposed. The two meso-scale damage modes, rupture and yield are considered, and the whole damage evolution process is driven by the principal tensile damage strain. The results show that the proposed statistical damage model can accurately predict the constitutive behavior in the uniform damage phase for concrete under biaxial tension. The damage mechanism is discussed in the view point of biaxial strength and deformation properties.
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