Papers by Keyword: Yield Stress

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Authors: Wen Yi Yan, Qing Ping Sun, Peter D. Hodgson
Abstract: The spherical indentation obeys Hertz contact theory when the applied load is within the elastic limit. Once the applied load is over the elastic limit, the indentation curve starts to deviate from the original purely elastic indentation curve. This deviation point, which indicates the start of the nonlinear deformation, is an important characteristic of a spherical indentation curve. The indentation force corresponding to the deviation point is related to a basic material constant, which is the yield stress for an elastic-plastic material or the transformation stress for a shape memory alloy. This relationship can be applied to measure the yield stress or the transformation stress from a simple spherical indentation curve. Detailed discussion on the relationship and the method is presented in this short paper.
2131
Authors: Yun Xing Shi, Isamu Matsui, Nai Qian Feng
Abstract: This paper investigates the effects of vitreous slag powders on the rheological properties of fresh concrete. It was observed that the fluidity of concrete increased noticeably, and the plastic viscosity decreased when vitreous powders were substituted partially for cement. It was demonstrated in the experiments that the fluidity effect of vitreous powders on fresh concrete can be correlated with the vitreous content of the powders.
223
Authors: Sung Cheol Yoon
Abstract: The truck that is used as running equipment for freight car support is a core structural part that supports the load of the car body and that greatly influences the safety of freights and vehicles, as well as their running performance. The running equipment is composed of truck frames, wheels and wheel axles, independent suspensions, and brakes. Among these components, the truck frame supporting the load of the vehicles and freights may be the most important one. This study was carried out to analyze the structure of truck frames and to determine whether they are safe when the maximum vertical load, breaking load, and front and rear loads are applied to them. This was done by subjecting the truck frames to stress tests and then measuring the stress on each of their parts. Before the load test, a structural-analysis program was used for the stress distribution analysis of the truck frame. To measure the stresses based on the results of the structural analysis, strain gages were attached to the surfaces of truck frames [1].
405
Authors: Sung Cheol Yoon, Jeong Guk Kim, Kwang Sun Baik, Byeong Choon Goo, Kang Youn Choe
Abstract: The truck that is used as running equipment for freight car support is a core structural part that supports the load of the car body and that greatly influences the safety of freights and vehicles, as well as their running performance. The running equipment is composed of truck frames, wheels and wheel axles, independent suspensions, and brakes. Among these components, the truck frame supporting the load of the vehicles and freights may be the most important one. This study was carried out to analyze the structure of truck frames and to determine whether they are safe when the maximum vertical load, breaking load, and front and rear loads are applied to them. This was done by subjecting the truck frames to stress tests and then measuring the stress on each of their parts. Before the load test, a structural-analysis program was used for the stress distribution analysis of the truck frame. To measure the stresses based on the results of the structural analysis, strain gages were attached to the surfaces of truck frames. The results of the stress tests showed that truck frames have a safe vehicle load design.
210
Authors: Xiao Lin Ma, Yu Run Fan
Abstract: The aging and shear rejuvenation behavior of a commercial printing ink have been studied experimentally using creep and oscillation modes. We observed that the printing ink has typical rheological characteristics: time-dependent, reversible and shear-thinning viscosity. Meanwhile, these properties are very strongly influenced by shear history, thus employing pre-shearing to obtain a standard test state is of vital importance. After pre-shearing, the quiescent ink undergoes structural evolution, i.e., aging, including a sol-gel (liquid-solid) transition on the early stage at room temperatures, the higher the temperature, the earlier the sol-gel transition occurs. The degree of aging and shear rejuvenation can be characterized by the waiting time after pre-shearing and the stress dependence of the power-law index. Finally, we use a time-stress superposition to obtain a universal master curve which is able to describe the aging behaviors of the printing ink. This study shows that the aging processes of printing ink for different waiting times are self similar, variation of waiting time just change the time scale and elastic modulus.
132
Authors: Patrick B. Berbon, Minoru Furukawa, Z. Horita, Minoru Nemoto, Nikolai K. Tsenev, Ruslan Valiev, Terence G. Langdon
1013
Authors: Muhamad Sani Buang, Shahrul Azam Abdullah, Juri Saedon
Abstract: Springback is a serious problem in the manufacturing industry due to errors that effects the appearance of the final product especially in the sheet forming process. This paper presents the review on past literature regarding factors that affects the amount of springback that occurs after the forming operation. This paper focus on 5 major elements that affects the value of springback including yield stress (σy), Young’s modulus (E), strain hardening exponent (n), Poisson’s Ratio (v) and thickness of the sheet (t). This 5 elements show that, increases in the value of (σy), (n), will increase the value of springback. The springback decreases with increasing of (t) and (E). While (v) has a small significant effect on springback. The effects of these factors can be used as a guide when considering further research on springback.
323
Authors: Fadhluhartini Muftah, Mohd Syahrul Hisyam Mohd Sani, Ahmad Rasidi Osman, Mohd Azran Razlan, Shahrin Mohammad
Abstract: Fire accident is considered as the one of most severe environmental hazards to building and infrastructure. Cold formed steel (CFS) beam has been used extensively as primary load bearing structural member in many applications in the building construction due to high efficiency in term of production, fabrication, and assembling in construction. This material must be well perform in fire incident in term of its integrity and stability of structural for a period of time. Hence, the assessment of the material properties of this material is greatly important in order to predict the performance of this structure under fire incident. The tensile coupon tests of CFS are according to BS EN 10002-1:2001. The CFS material G450 with 1.9 mm thickness is used in this study. The elastic modulus, yield stress, correspondent percentage strain at yield stress, ultimate stress, and correspondent percentage strain of ultimate stress was 200.3 GPa, 540.5 MPa, 0.478 %, 618.8 MPa, and 8.701 % respectively. The results of the ambient temperature test have been used to assess the mechanical strength of CFS at elevated temperature. The discussion of material properties is based on EC3-1-2 and proposed model from other researchers. The main material properties discussed is the stress-strain curve, elastic modulus, yield strength at elevated temperature was determined. The actual elastic region is slightly lower than the prediction of EC3-1.2 at ambient temperature, but well fit with two other studies. Besides that, the actual material properties experience strain hardening after yielding and reach a maximum stress up to 618 MPa while EC3-1.2 predict the constant value of the yield stress after yield until 15 % strain,other two study was fit the ambient tensile test up to ultimate stress, and fit until 2 % strain level.
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Authors: Fan Jin Hu, Shen Jie Zhou, Feng Ling Yang, Lei Shi
Abstract: The 3D flow field generated by two-stage impellers in the agitation of xanthan gum, a pseudoplastic fluid with yield stress, was simulated using the commerical CFD package. The effect of impeller speed and impeller spacing on power number, cavern size and viscosity distribution was investigated in this work. The results showed that the power number was slightly influenced by impeller spacing. Higher impeller speed and larger impeller spacing contributed to creation of a bigger cavern. The range of high viscosity zone between the impellers increased with an increase in impeller spacing. Impeller speed and impeller spacing could be used as important parameters to improve the mixing performance of multi-stage impellers in the mixing of pseudoplastic fluids with yield stress.
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