Papers by Keyword: Material Parameter

Abstract: Bamboo building envelope (BBE) is a kind of hygroscopic construction, making it necessary to describe the coupled heat and moisture (H&M) process accurately. In order to clarify the impact of material parameters on the H&M process of BBE, the study sets up BBE comparison model groups in WUFI Plus for annual coupled H&M process simulation, with exterior walls of 3 typical bamboos as boundary conditions and climate data of 24 Chinese representative cities as external conditions. Results quantitatively show the factor impact of hygrothermal properties parameters on the annual moisture content, heat and moisture exchange of the bamboo exterior walls, as well as the HVAC demand and indoor hygrothermal environment of the bamboo enclosed space. The simulation without liquid water-related parameters results in significant underestimation of moisture content and moisture exchange, and causes evident deviation to the heat exchange and HVAC demand. The constant valuation of thermal parameters and hygric parameters lead to deviation in heat process and moisture process of the BBE, respectively. The study highlights the moisture content-dependent bamboo hygrothermal parameters for the application of BBE.

Abstract: The improved plane wave expansion method is used to investigate the effects of material parameters on the longitudinal vibration band gaps in thin phononic crystal plates. Both square lattice and graphite lattice are considered. Results show that the parameters playing the essential roles are the mass density ratio and the Young modulus ratio of the scatterers and the host materials.

Abstract: A new device to measure the material parameters of Baushinger effect from cyclic bending tests, along with its associated test procedure is presented. This new apparatus is designed to get a large range of stains obtained from part geometry directly. The parameter identification is defined by an optimization algorithm with multiple objective iteration function for variance method. The experiment method, design procedure is documented, along with experimental procedure supporting our conclusions.

Abstract: A regularization based method of inversely analyzing the material parameters for the gravity dams is presented in this paper. The measured noise of the displacement often leads to the ill-posed solutions of the dam inversion. A least square scheme was adopted for the inverse analysis by using of the displacement measurements, and the L-curve algorithm was proposed to perform the regularization in the inversion computation. The proposed method actually utilizes the sensitivity of the measured displacements with respect to the sub-regional material parameters. Thus a simplified algorithm was developed to calculate the sensitivity coefficients by using the standard finite element procedure. To investigate the effectiveness of the proposed method, the numerical simulations on a concrete gravity dam were carried out. The results demonstrate that the presented method can accurately obtain the material parameters of the dam by using of the inverse analysis, which has the potential for assessing the integrity of the gravity dams.

Abstract: In conventional analysis of instability, a rough prediction of uniform deformation was obtained due to taking material parameters as constants. In this study, the constitutive equation with varying parameters for Zn-5%Al alloy at 340 °C is employed to predict the critical values of uniform strain in tension based on Considere criterion and Hart criterion, respectively. It should address the factor of strain rate in the characterization of the capability of uniform deformation on superplastic alloys, or for that matter, on any rate-dependent material. Comparison and analysis indicated that the results on Hart criterion have the better predictability of uniform deformation than Considere criterion. The Considere criterion is dependent on strain path, while Hart crtierion is merely dependent on the values of strain and strain rate in tension, and is independent on the strain path or the deformation condition or the deformation history. Therefore, the uniform strain vs. strain rate relation can be taken as a quantitative reference for designing a reasonable strain path during superplastic forming with increase of formability and reduction of forming time.

Abstract: With the development of numerical calculation and precision forming, constitutive equations are required to possess high accuracy and good reliability, rather than simplicity of mathematical form. Due to simple algorithm and constant parameters, the conventional constitutive models can not be suited to describing superplastic flow behavior which represents complex responses with a large strain. In this study, through surface fitting on experimental data from tension tests performed over a wide range of strain rates, tensile velocities and loads, an empirical approach was proposed to establish constitutive equation for complex superplastic behavior of Zn-5%Al alloy at 340 °C. The empirical constitutive equation not only represents the strain dependence and the strain rate dependence of stress, but also reflects the coupling effects of strain and strain rate on stress, which can not be achieved by traditional models. A comparison between the predicted flow stresses and the experimental data verified that the empirical constitutive equation has high accuracy and good reliability on modeling superplastic flow behavior of Zn-5%Al alloy at 340 °C in a wide range of strains 0~2.5 and strain rates 7.0×10^-5~8.0×10^-2 s^-1.

Abstract: The point of quantum and immunity algorithm is concluded. A identify model of quantum and immunity algorithm network is constructed. The input and output design of pipe retracting shape parameter is given, and the collection and deal of sample data is also given. Using quantum and immunity algorithm network does the imitate sample of model. The identify result of satisfaction is given. The new field of the pipe retracting shape parameter identify of quantum and immunity algorithm network is opened.

Abstract: In the analysis of engineering structures are usually adopt the method of fixed value, that is the practical engineering structure under load and the performance of materials used by structure shall be treated as a constant value.But, in fact, the structure of geometry size, bear the load, material parameters,computing model and so on are affected by various factors. In order to more accurately reflect the reliability problems of reinforced concrete structures, this paper, the factors above will be regarded as random variables, combining the basic theory of reliability design, through the probability analysis, in normal uselimit state reliability of reinforced concrete structures for example analysis of the influence of related parameters on the structural reliability.

Abstract: Identification of a bird constitutive model and its parameters is a very difficult work in bird-impact coupling solution. In order to identify the constitutive model and the parameters simultaneously, an inversion analytic model for the bird material parameters is given based on penalty function method and nonlinear optimization principle, and then combining the model preferential criterion proposed in this paper, the identification system of the bird constitutive model is established with ANSYS Parametric Design Language (APDL). Finally, the feasibility and practicability of this identification method are verified by an example.

Abstract: The drivers were hurt seriously by the vehicle steering column in the frontal collision. So a steering column with well energy-absorbing is very useful for the drivers. In this paper, the crashworthiness of a vehicle steering column is investigated by using the explicit dynamics finite element analysis method. Based on the proposed finite element model, the steering column with different material parameters including elastic modulus and yield strength are analyzed. Moreover, the displacement, velocity and energy absorption is discussed. The simulation results show that the crashworthiness of the vehicle steering column is significantly influenced by the yield strength. However, the elastic modulus has little effect on the crashworthiness.