Papers by Keyword: Constitutive Relations

Abstract: The topic of this paper is the short review of current state-of-the-art in the field of material models of concrete and its utilization for numerical analysis of concrete and prestressed concrete structures. The problem of compiling constitutive relations for numerical simulation of concrete structures is not yet closed. It is caused by different behavior of concrete in tension and compression. Due to formation and development of cracks it is necessary to describe material model of concrete in tension as precisely as possible. The paper aims to create a brief historical overview in this field and then aims to create a short summary of current approaches that were published in conference contributions and in journals during recent years.

Abstract: The general structure of the multilevel models of inelastic deformation of materials including the internal structure evolution description was considered in the present paper. It also provides variants to address the key issues of similar type models, which are important for further development of such models. A new approach for constitutive relations coupling between constitutive relations of different scale levels was described. The suggested approach establishes connection of similar characteristics in different scale levels. The proposed coupling method also provides an unambiguous determination of material frame indifferent derivative of the Cauchy stress tensor at the macro scale, which is necessary for the formulation of constitutive relations for large deformations. In order to make it clearer an example of a two-level model of polycrystalline metals is considered; based on the physical sense analysis the hardening laws and lattices rotations of crystallites are suggested.

Abstract: The nonlinear finite element can precisely simulate practical work condition of arch dam, but also has some problems in the safety evaluation of high arch dam, mainly in different mesh size, different strength criteria and constitutive relations of dam corresponding to different results. This article first proposes determining method for reasonable mesh size describes three strength criterions of uniaxial, biaxial, triaxial, gives two constitutive relations of dam cracking, damage. Take a high arch dam as an example, has done some research on the above question, obtain some beneficial conclusions.

Abstract: A new rationale to assess the work-hardening locus for pre-rolled sheets is described based on the realization that since the internal stresses necessarily sum to zero, the mean dislocation density remains the same upon re-pull in the rolling direction. Thus the 0.2 % yield stress as function of thickness strains results in an estimate of the stress-strain relation during rolling. Under plane strain, the thickness strain is negative to that of extension and hence the deduced rolling locus is compared to that of extrapolated tensile one of the start sheet. This comparison indicates that the onset of Stage IV occurs when volume fraction of point defects produced attains about 2 %.

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: Stainless steels of different types and grades are being developed world over to meet ever increasing demand for enhanced materials performance. Advanced stainless steel products have applications in a variety of industries including nuclear, defence, space, chemical, oil and gas, medical and appliance. It is understood that the properties of the alloys strongly depend not only on the chemical composition but also on their microstructure, which in turn depends on parameters in the manufacturing process. Therefore, the challenge to the manufacturing industry is not only selection of optimum composition but also relevant manufacturing processes to meet the requirements. Designing a manufacturing process and optimum process schedules using experimental trials is both time consuming and expensive. Modeling and simulation play an important role to reduce these times effectively. This paper presents important points to be considered to produce clean steels and highlights the applicability of modeling techniques that can be effectively applied in a manufacturing industry. Some of the case studies that are included in the paper are Computational Fluid Dynamics model to understand gas atomisation Finite element modeling of compound tube extrusion In conclusion, the power of modeling and simulation to understand manufacturing processes is highlighted.

Abstract: A general formulation of constitutive relations in non-smooth elastoplasticity is presented. The treatment applies to general non-smooth plasticity problems and to problems characterized by non-smooth yield criteria or dealing with non-differentiable functions. The mathematical tools and instruments of convex analysis and subdifferential calculus are suitably applied since they provide the proper mathematical instruments for dealing with non-smooth problems and non-differentiable functions. General formulations of constitutive relations and evolutive laws in non-smooth elastoplasticity are illustrated within the presented theoretical framework. Connections between the proposed mathematical treatment and the classical relations in elastoplasticity are illustrated and discussed in detail. The presented generalized treatment is equipped with considerable advantages since it shows to be ideally suited for the development of variational formulations of structural problems in non-smooth elastoplasticity.

Abstract: Constitutive relations are presented for a model of nonlocal viscoplasticity within a variationally consistent suitable setting. The appropriate elastic and dissipative potentials are introduced within a generalized standard material framework. A formulation of variationally consistent constitutive relations is accordingly presented for a model of nonlocal viscoplasticity. The evolutive equations are illustrated for the proposed model in a general form which is able to include different models of nonlocal viscoplasticity and different hardening rules.

Abstract: A general treatment of constitutive relations in elastoplasticity and elasto/viscoplasticity is presented. The treatment holds for general non-smooth problems and it applies to non-smooth yield criteria and to functions characterized by non-differentiability. The formulation is developed by resorting to the tools provided by convex analysis and subdifferential calculus which are the appropriate instruments for dealing with convex criteria and non-smooth functions. General formulations of constitutive relations and evolutive laws are presented for elastoplasticity and elasto/viscoplasticity and connections are illustrated between the general elastoplastic model problem and the general elasto/viscoplastic model problem. The presented generalized treatment proves to be well-suited for the development of variational formulations for structural problems in elastoplasticity and elasto/viscoplasticity.

Abstract: Magnetorheological materials belong to a kind of new intelligent materials and their application prospect is very optimistic, however electromagnetic relations are very complex, and with the outside world and boundary conditions have close relations, so each model and theory has its pertinence and limitations, hard to get the universal unified the constitutive relations, so this paper based on energy, gets a set of magnetorheological materials about the theory.