A discrete element method for modelling fracture evolution of roadway surrounding rock is provided, which includes: taking rock cores from a coal seam in the field and recording RQD values, observing roadway deformation, and making a statistical analysis on distribution characteristics of fractures in the coal seam; testing mechanical parameters of coal-rock samples indoors, and calculating strength of a rock mass according to the RQD values; creating a numerical model by using a UDEC-Trigon module to adjust the parameters to match the strength of the rock mass, and correcting model parameters; and creating a numerical model of an engineering scale to adjust the parameters to match field deformation characteristics, and finally simulating fracture evolution of the roadway surrounding rock. The present invention provides accurate and basic mechanical parameters for discrete-element numerical simulation of roadway deformation, guaranteeing realistic and reliable simulation results.

A signal processing method and a material testing machine are provided. A reference function processing part includes a data interval generation part for cutting out input signal from a load cell into time-domain data interval by cutting out the input signal of a predetermined time length, a reference function determining part for determining a reference function to be used in a transform process, and a transform part for transforming the interval data using the reference function. Considering the approximately straight lines near the two ends of the data interval, the reference function is a third degree polynomial function with tangents overlapping with the approximately straight line at both ends of the data interval.

The invention discloses a method for obtaining the geometrical and mechanical parameters of rock samples and a holographic scanning system thereof, wherein the system includes an observation mechanism, a multi-scale penetration mechanism, a grinding mechanism, a rock sample installation mechanism arranged on a three-axis precision motion platform, and an industrial computer controlling the operation mode of each mechanism of the platform Indentation/rotary penetration test, pulse echo signal acquisition, three-dimensional surface topography reconstruction, layer by layer grinding and repeated experiments are carried out. The geometric parameters and corresponding mechanical field parameters are obtained by spatial interpolation of the three-dimensional parameter lattice accumulated by several layers of single-layer rock parameters. The holographic scanning system and method can obtain the real spatial distribution of various media in rock samples. Combined with high performance numerical calculation method, it provides a more scientific method for the analysis of rock mechanical properties, failure and instability.

A system includes a load actuator, a strain measurement device, and a computing device. The computing device is configured to receive an unconditioned displacement signal from the strain measurement device. The unconditioned displacement signal represents displacement of a specimen under load from the load actuator. The computing device is further configured to split the unconditioned displacement signal into a measurement signal and a control signal. The computing device is further configured to filter the control signal to generate a filtered control signal and control the load actuator based on the filtered control signal. The computing device is further configured to determine a strain on the specimen based on the measurement signal.

Provided is an analysis apparatus configured to analyze characteristics of a viscoelastic material based on a viscoelastic material constitutive law in which an elastic element and a viscoelastic element are arranged in parallel with each other; calculate, in a viscoelastic material model divided into a finite number of elements each having a node, a displacement amount of the node; calculate a strain rate at the node through use of the displacement amount; calculate, as a relaxation time of the viscoelastic element, a value proportional to a value of a power using the strain rate as a base and a value of a power using a shift factor of a temperature-time conversion law as a base; and calculate a stress at the node through use of the relaxation time.

A material testing machine is provided. The material testing machine includes a force detector that detects the testing force that acts on the target to be tested; a displacement detector that detects displacement generated in the target to be tested; and a controller that controls the load mechanism. The controller includes: a differential displacement calculator that obtains a differential displacement value from a value of the displacement detected by the displacement detector and a target displacement value that has been set in advance as a test condition; and a display controller that displays, on a display device, a differential displacement graph indicating, in a form of a graph, time-series data of the differential displacement value calculated by the differential displacement calculator.

Systems and methods for determining mechanical properties of formation rock using, for example, millimeter-scale test samples of the formation rock are disclosed. The test samples may be single edge notched beam (SENB) test samples. The systems and methods may include performing laboratory testing on the SENB test samples and recording laboratory testing data obtained from the laboratory testing and performing a simulation on a numerical model of the SENB test samples and recording the simulation data obtained from the simulation. The laboratory testing data and the simulation data may be compared, and a determination may be made as to whether a selected degree of correlation is present between the laboratory testing data and the simulation exists. Mechanical properties of the formation rock are obtained from the simulation data when the selected degree of correlation exists between the laboratory testing data and the simulation data.

A method for estimating life of a component includes obtaining fracture data corresponding to a component. The fracture data includes a first dataset corresponding to a threshold region where the crack in the component is dormant below a fatigue threshold. The method further includes determining initial estimates of parameters of a crack growth rate model and parameters of temperature models corresponding to the crack growth rate model based on the fracture data. The method also includes computing optimized parameters of temperature models corresponding to the crack growth rate model, and a scatter parameter via simulation of a joint optimization method using the initial estimates. The method includes determining a cumulative distribution function based on the optimized parameters and the scatter parameter and estimating life of the component based on the cumulative distribution function.

The invention provides a method and device for measuring the elasticity of hardened cement for cementing of oil-gas wells. The measurement method comprises: determining the loading and unloading rates of the hardened cement; determining the maximum loading on the hardened cement; determining the experimental temperature and the experimental pressure of the hardened cement; establishing a stress-strain curve for the hardened cement; and describing the elasticity of the hardened cement with the degree of strain recovery of the hardened cement in different cycles, and describing the mechanic integrity of the hardened cement with the degree of damage to the hardened cement in different cycles. The invention further provides a device for measuring the elasticity of hardened cement for cementing of oil-gas wells. The measurement method and device of the present invention provide a universal comparing platform for research on hardened cement modification as well as examination of domestic and foreign special cement slurry systems, which is of great significance in evaluation of well hole integrity and well life.

Provided is a material testing machine (1) including: a load mechanism (12) that applies a load to a test object; a load measurement device that measures the load applied to the test object; and a control device (30) that performs a feedback control for the load mechanism (12) based on a deviation between a measurement value of the load and a target value of the load, in which a change in a physical quantity generated in the test object due to the load is measured, and the control device (30) includes a hunting detection unit (66) that detects hunting by comparing a frequency spectrum obtained by converting time-series data of the measurement value with a frequency spectrum obtained by converting the time-series data of the target value.