Papers by Keyword: Stress-Strain Curve

Abstract: The contribution deals with prediction of tensile properties based on measurement of microhardness. First of all, the database of stress strain, s-e vs. hardness data was created. Tensile strength, yield strength, ductility and parameters of Ludwig-Hollomon equation σ = σ₀+kεⁿ ; k, n were correlated with hardness. Various hardness values found in literature were recalculated to Brinell hardness. In tensile testing measured s-e curves were compared with that obtained from the correlation. The investigated materials were API 5 L grade steels X70 after different deformation exposition. The results give good agreement between compared data. The most difference between estimated and measured curve is in area of yield strength, because of Lüders deformation on investigated steel.

Abstract: Green high performance fiber reinforced cementitious composites (GHPFRCC) is the optimized mix proportion of engineered cementitious composites (ECC) with high volume of fly ash and polyvinyl alcohol (PVA) fiber. To study the compressive performance, the prism stress-strain relationship of GHPFRCC is the focus in this study. There are sixteen groups of GHPFRCC specimens with the size 40mm×40mm×160mm. The compressive stress-strain curves were obtained based on the uniaxial compression tests. Experimental results show that the uniaxial compression stress-strain curve belongs to the skewed unimodal curve. The peak strain can steadily reach more than 0.005, and it has put up a great plastic deformation capacity and post-peak ductility. It has still reserved some residual strength even when the strain is up to a bigger value. The research achievements can promote the application of GHPFRCC in the practical engineering.

Abstract: In order to acquire axial tensile stress-strain curve of HFRC, specimens of equal cross-sections with embedded screw and pasted with carbon fiber cloth in corresponding length were tested on closed-loop electro-hydraulic servo testing machine which a subsidiary rigid frame was attached to. The effect of fiber volume, steel fiber slenderness ratio, steel fiber type and active admixture on the tensile properties of HFRC with low volume fraction was studied. The results indicate that when total volume proportion is less than 1% the first crack strength and ultimate tensile strength of HFRC can increase more than 15% and about 40% , respectively, the difference of effect of arched steel fiber and crimped steel fiber on the tensile behavior is small. The tensile behavior of HFRC is the best with a combination of slenderness ratio of 80 and 47.1kg/m³ arched steel fiber, 2.6kg/m³ macro-polypropylene fiber and1.0kg/m³ dura fiber and 10% .

Abstract: As the largest solid waste in China, iron tailings have brought a huge impact and potential safety hazard to resources, environment and land. In this paper, using the stress-strain controlled soil mechanics tri-axial apparatus, the author researched the mechanics performance of the cement stabilized iron tailings in the laboratory. The result shows: Along with the increase of the cement dosage, stabilized material strength has improved significantly; Under the confining pressure from 300kPa to 500kPa, the increase of confining pressure is proportional to the strength of stabilized material. Moreover, lower cement content (3%-5%) of stabilized material, its stress-strain curve is similar to those of clayey soil, it has clear plastic yield characteristics; on the contrary, higher dosage of cement stabilized material (7%-9%), the plastic reduced and strength increased. Keywords: cement stabilized iron tailings; cement dosage; stress-strain curve; strength; confining pressure

Abstract: Under unloading condition, the characteristics of rock are different from them under loading condition. This paper talks about the characteristics of Ordovician limestone under loading and unloading condition of high compress which were taken from North Tian Mountain. The testing results indicated that: The lateral deformation and bulk deformation of rock sample are clearly in the process of unloading. Plastic deformation is not notability in the unloading condition. After the peak value in the stress-strain curve, the stress decrease quickly, it is showed that the brittleness characteristic is the better remarkable under unloading condition than loading condition. Under unloading condition, deformation modulus E₅₀ and Possion ratio μ is quadric with the confining compress.

Abstract: This report reviews biomimetic studies performed in China on the beetle forewing, noting that Chinese scholars studying bionics have substantially advanced various branches of biomimetic research in beetles. The report also proposes the development of branches of bionic research and establishes the foundation for corresponding experiments and theories. Then, using the A. dichotoma forewing as a an example, the cross-sectional shape, orientation of the laminated fiber layers, structure of the trabeculae, and respective mechanical properties of the forewing, as well as their biological significance, are reviewed. 1) The forewing has a lightweight border frame structure and an optimal design of variable cross-sections suitable for different positions, which achieves the specific second moment of inertia required for flight. 2) Due to the non-equiangular, laminated structure of the forewing, there are two types of tensile fracture morphologies: fiber breakage and residual bridging. This study demonstrates the anisotropy and the effectiveness of the forewings tensile strength by analyzing the orientation direction of the fibers. 3) The trabecular structure can be used to efficiently improve the peel resistance of the laminated composites. Based on the above points, possible directions for future work are also indicated in this paper.

Abstract: Forming process of TC4 titanium alloy laser weld joint during superplastic deformation is simulated. The stress and strain curve, which is obtained in the simulation, is compared with that obtained by hot tensile experiments. The simulation results provides a basis for subsequent laser welding / superplastic forming technology, and proposes outlook to the analyze problems for laser welding / superplastic forming (LBW / SPF) technology.

Abstract: Study of Constitutive relations of concrete based on Chinese and foreign scholars. This paper put forward constitutive equation that more close to the stress-strain data of high strength concrete under uniaxial compression, and make a comparison between the theoretical results and experimental data, and promising results were obtained. It can be used as a basis for researching of high strength and high performance concrete of other mechanical properties.

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.

Abstract: In order to investigate the anti-crush properties and the corresponding deformation mechanism of hollow integrated woven textile sandwich composites (IWTSCs), the quasi-static out-of-plane compression experiments are carried out. A set of typical deformation curves with a relative stable deformation plateau are obtained. The coupled compression-shear deformation and the ductile failure mechanism of IWTSC is discussed. Combining with qualitative analysis, comparisons between three kinds of IWTSC panels with piles of different density and thickness reveal the key to design a ductile IWTSC.