In this paper, an elastoplastic constitutive model is presented for predicting sandy soil behavior under monotonic and cyclic loadings. The model is based on the CJS3 model that takes into account deviatoric and isotropic mechanisms of plasticity. The flow rule in deviatoric mechanism is non-associated and a kinematic hardening law controls the evolution of the yield surface. In the present study, the critical state surface and history surface separating the virgin and cyclic states in the stress space are defined. Hardening modulus and stress-dilatancy law for monotonic and cyclic loadings are effectively modified. Taking the hardening modulus as a function of deviatoric and volumetric plastic strain, the model will be capable of predicting sand behavior once the history surface and stress reversal are defined. All model parameters have clear physical meanings and can be determined simply from laboratory tests. The results of homogeneous tests on Hostun sand are used to validate the model. The results of validation indicate the capability of the proposed model.

New techniques in seismic design of structural systems are based on flexibility and energy dissipation approach. In this approach, the role of energy dissipaters is quite important. The behaviors of these devices and the way they dissipate energy have always been a concern for many researchers to improve the efficiency of these important parts of the structural systems. There has been a large number of investigations on behavioral aspects of energy dissipating devices capable of using in seismic design of structural systems.The concept of adding dissipating supplemental devices to a structure assumes that much of the energy imposed to the structure from a transient will be absorbed, not by the structure itself, but rather by supplemental damping elements. Among them, viscous devices have received considerable attention. The behavior of these energy dissipaters are dependent, not only on the relative velocity, but also on a large number of other parameters including relative displacement, compressibility of fluid, internal friction etc.The behavior of viscous devices are also dependent on the frequency of excitation and their thermal conditions. Determination of mechanical characteristics of these devices is usually based on experimental studies including cyclic tests in different amplitudes and frequencies.In this study, a new type of viscous dashpot in which the main body of the device has been made of contractible steel bellows (developed in IIEES) is chosen for experimental studies. The viscous device has the capacity of 500 kN and axial deformability of ±150mm. The tests have been carried out using an actuator capable of providing axial forces up to 300 kN in cyclic tests with displacement range of ±120mm. Axial forces on dashpot and resulted deformations on the device during experiments have been used to find the relationships between applied forces and induced relative displacement and velocity on the device.According to the results, the dashpot shows a dominant viscous behavior. It also represents a small frictional behavior in order of 10 kN (on average). The device also shows a frictional feature that is proportional to its internal fluid pressure. This feature is due to a small asymmetry in manufacturing some parts of the device, but it can be used later to improve the behavior of contractible dashpots. To be able to develop a model for this device, the test results are used in the form of cyclic behavior and time series. The time series results show the fact that there is not a linear proportionality between forces and velocity experienced by the dashpot in all the range of excitation frequencies. In addition, according to the test results, damping constants for this device is also dependent on the excitation frequency. Different types of behavioral models have been examined for the device. The proper model is proposed based on the three element type Maxwell model. The model can be further improved to represent the pressure dependent frictional forces in this dashpot.

In the last three decades, the constitutive modeling of concrete evolved considerably. This paper describes various developments in this field based on different approaches such as elasticity, plasticity, continuum damage mechanics, plastic fracturing, endochronic theory, microplane models, etc. In this article the material is assumed to undergo small deformations. Only time independent constitutive models and the issues related to their implementation are discussed.      

The present paper deals with the theory of Ibn Sina's certain judgmental knowledge in terms of determining its constituent parts. Given Ibn Sina's existing ideas, these constitutive elements include belief, bi-dimensionality of belief, stability, and existence of middle term (in non-axioms). Nevertheless, regarding the notion of truth, we should say that Ibn Sina's considering it a constituent part creates several problems. The writer believes that since this point has not been directly stated in Ibn Sina's views, truth is necessary for a specific type of certain affirmative knowledge. Truth is neither a constituent of certain judgmental knowledge nor something external to it, rather, it is necessary for it.

Constitutive model of passive myocardium of lamb: Experimental tests and equations on the continuum mechanics are used in order to obtaining the constitutive models of soft tissue using in predictive heart simulation. Considering the myocardium as one of the important tissues, in this paper first the morphology and structure of myocardium has been reviewed and the mechanical response of passive form of this tissue has been investigated. The myocardium of left ventricle was considered as non linear elastic, in-compressible and non homogeneous material and using of bi-axial test in 3 lambs myocardium on fiber direction; a constitutive model of this tissue has been proposed. The model so constructed is then evaluated against the biaxial data, and values of the material constants have been obtained by curve fitting so the final model states the strain-energy function as cauchy's invariants which can be helpful in heart simulation.

In this article, while analytically reviewing the Landau formalism for electrodynamic equations in the presence of a gravitational field, we show that the three-dimensional electromagnetic constitutive relations in this formalism can be expressed by two equivalent methods. Then we obtain the constitutive relations for the Galilean rotating observer with both methods and show its compatibility with the previous results. We also present the electromagnetic constitutive relations for an eccentric rotating observer. To solve some ambiguities, especially in the articles related to this topic in the field of electrical engineering, different representations of the three-dimensional form of constitutive relations in the Galilean rotating observer’s frame are expressed in full detail. Also, the connection between different representations of three-dimensional constitutive relations will be explained. In the end, considering the practical and experimental importance of the eccentric rotating observer, we will obtain the electromagnetic constitutive relations for this particular observer.

There was and to some extent still is a good habit in some of the authors of text books. They begin their books by explaining different constitutive elements of the Science in question. The idea of explaining the subject matter, the conceptual and propositional primary principles and the problems of that field of the study is so important that without them we will not be able to understand it fully. In this paper, explaining Avicenna's view on the constitutive elements of the science, we try to show the importance of the subject matter in distinguishing a specific branch of knowledge from others.

The behavior of concrete structures that are exposed to extreme thermo-mechanical loading is an issue of great importance in nuclear engineering. The structural re-safety capacity of concrete is very complicated because concrete materials have considerable variations. Constitutive models and relationships for preloaded Normal and High Strength Concrete (NSC and HSC) subjected to fire are needed, which are intended to provide efficient modeling and to specify the fire-performance criteria of the behavior of preloaded concrete structures exposed to fire. In this paper, formulations for estimating the parameters aecting the behavior of uncon ned preloaded concrete at high temperatures are proposed. These formulations include residual compression strength, initial modulus of elasticity, peak strain, thermal strain, transient creep strain and the compressive stress-strain relationship at elevated temperatures. The proposed constitutive models and relationships are veri ed with available experimental data and existing models. The proposed models and relationships are general and rational, and have good agreement with the experimental data. More tests are needed to further verify and improve the proposed constitutive models and relationships.