8 results about "Material constants" patented technology

The present invention relates to a discrete dislocation dynamics modeling method considering twin evolution, the method comprising: constructing a discrete dislocation dynamics geometric model based on the material constants of a target material and the computational information required for simulation; applying preset plastic deformation boundary conditions to the target material to determine the microstructural changes of the target material during the plastic deformation process; when twin nuclei exist in the target material, calculating the growth rate of the twins and determining the twin evolution size based on the growth rate; in the geometric model, defining an elliptical twin boundary according to the twin evolution size, and implementing a slip plane direction reconstruction algorithm within the twin domain to update the crystal orientation and dislocation source position in real time to simulate the growth of twins; after the twin growth is completed, iteratively correcting the dislocation evolution in the target material according to the twin growth state. In this way, the authenticity of the material plastic deformation simulation can be improved.

The invention belongs to the technical field of metal material hot working, and provides a method and system for constructing a thermal deformation constitutive model of a spray-formed 2195 aluminum-lithium alloy, and the method comprises the following steps: obtaining flow stress data according to a hot compression test; correcting the flow stress data to obtain calibrated flow stress data; identifying a peak stress and a material constant according to the calibrated flow stress data, and summarizing a Z parameter expression; introducing a strain influence function according to the material constant, and fitting a strain function; and substituting the strain function into the Z parameter expression to obtain a constitutive model. According to the method, the high-precision constitutive model considering the strain influence is established for the extrusion state spray forming 2195 aluminum lithium alloy for the first time, material parameters under different strains are identified through a system, the applicability of the model in a large deformation forming process is remarkably improved, and the prediction error is lower than 5%; a reliable theoretical tool is provided for formulating a hot working process, the trial and error cost is reduced, and the product quality and the structure uniformity are improved.

The present invention discloses a method for constructing a mechanical constitutive model for two-dimensional woven composite materials, belonging to the field of mechanical property characterization and analysis of two-dimensional woven composite materials. The method is divided into two parts: geometric nonlinearity caused by fiber redirection and material nonlinearity caused by plastic behavior. The establishment of the method includes the following processes: step 1, determining the initial material constants of the orthotropic constitutive model; step 2, analyzing the transformation of material properties with applied deformation to determine the geometric nonlinear parameters; step 3, establishing a plastic constitutive model and determining the material nonlinear parameters. The method of the present invention can ensure that the two-dimensional woven composite material still has orthotropic anisotropy under finite deformation, and can accurately and reliably predict the stress-strain response of the two-dimensional woven composite material after fiber redirection under finite deformation, providing a reliable constitutive model for the characterization and analysis of the mechanical properties of two-dimensional woven composite materials.

The invention discloses an indirect calculation method and system for surface energy of a hard and brittle material at a high temperature, and the method comprises the steps: measuring the fracture toughness of the material at a normal temperature through an indentation method, measuring the surface energy through a contact angle method, measuring the elastic modulus through a pulse excitation method, and calculating a material constant based on a Griffith energy balance equation; then, measuring fracture toughness and elastic modulus at different temperatures in a high-temperature environment, and fitting to obtain a function relationship of the fracture toughness and the elastic modulus along with temperature change; and finally, based on the material constant, the high-temperature fracture toughness function and the elastic modulus function, the surface energy at the high temperature is obtained through calculation. The high-temperature surface energy of the hard and brittle material is quantitatively calculated by measuring and calculating mechanical property parameters of the hard and brittle material at different temperatures.

The invention discloses a method for determining a low-cycle fatigue life prediction model based on strain rate sensitivity, a prediction method and a related device, and relates to the field of fatigue life prediction of high-temperature structural materials.The method comprises the steps that firstly, a reference strain rate is selected, and a uniaxial tensile test is conducted on a sample component; obtaining net tensile hysteresis energy and low-cycle fatigue life of different strain amplitudes at the reference strain rate; and based on the data, utilizing a classic energy life model to obtain a material constant parameter. And performing a uniaxial tensile test on the sample component to obtain the tensile plastic strain energy density of each strain rate in the strain rate range. And obtaining a change factor of each strain rate based on the tensile plastic strain energy density of each strain rate. And based on each strain rate change factor, the material constant parameter and the classical energy life model, obtaining a corrected energy model of each strain rate. According to the method, the low-cycle fatigue life of the material in a wide strain rate range can be accurately predicted.

To provide a technique for more simply estimating the fracture life of a rubber composition.SOLUTION: A method for estimating a fracture life of a rubber composition includes a step of acquiring a material constant of a test piece of a target rubber composition, a step of acquiring a repeated strain condition or a repeated stress condition, and an estimation step of calculating a crack growth rate of the test piece or a number of times at fracture indicating the number of times of the repeated load at which the test piece fractures, by using the material constant and the strain condition or the repeated stress condition, assuming that the repeated load acts on the test piece of the target rubber composition in a repeated tensile test.SELECTED DRAWING: Figure 1

The invention discloses a method for determining the relationship between workpiece diameter variation and treated workpiece surface performance parameters, which is applied to the field of metal material performance detection and comprises the following steps: establishing a quantitative relationship model between the workpiece diameter variation of a workpiece and the workpiece grain size of the treated workpiece; performing surface nanocrystallization treatment on the workpiece to obtain workpiece grain sizes of the treated workpiece corresponding to different workpiece diameter variations, and obtaining a plurality of groups of experimental data; experimental data are substituted into the quantitative relation model, model parameters are fitted through a least square method, and the model parameters comprise to-be-calibrated material constants related to the to-be-tested workpiece material; and according to the model parameters, the relation between the workpiece grain size of the processed workpiece and the workpiece diameter variation is determined. According to the method provided by the invention, the industrial implementability of the workpiece surface nanocrystallization treatment can be remarkably improved, the performance detection efficiency of the treated workpiece is improved, and the comprehensive cost is reduced.

The present application relates to hydrogen energy transportation and material mechanical property testing technical field, specifically to a kind of high-pressure hydrogen environment hydrogen transportation pipeline material constant load fracture toughness efficient determination method, by precasting the crack depth corresponding to different stress intensity factor level in two compact tension specimens respectively, and using orifice plate to mechanically connect the two, make two specimens simultaneously bear the same constant tensile load in high-pressure hydrogen environment, and after the fracture of any specimen, load can still be stably transmitted to another specimen, so that the crack propagation response data under two different crack depths in single constant load test is simultaneously obtained.The present application effectively utilizes the test time resources, and makes the test efficiency more than doubled.