49 results about "Strain difference" patented technology

The invention relates to the technical field of gradient material mechanical analysis, in particular to a calculation method of a gradient material macro equivalent elastic modulus, and the problem that the acquisition efficiency of an existing gradient material macro equivalent elastic modulus is low is solved. The calculation method comprises the steps that relation expressions of the average stress sigma bar of a homogeneous medium layer and the internal stress of materials of all phases are obtained; a relation expression of a disturbance strain difference epsilon' of an inclusion phase and equivalent eigen strain epsilon* is obtained; a disturbance stain difference sigma', disturbance stress sigma bar of a primary phase and disturbance stain epsilon bar of the primary phase are obtained; relation expressions of the homogeneous medium layer average stress sigma bar and the average strain epsilon bar are determined; equivalent moduli L of all homogeneous medium layers are obtained; equivalent bulk moduli K and equivalent shear moduli G of all the homogeneous medium layers are obtained. According to the calculation method of the gradient material macro equivalent elastic modulus, macro equivalent elastic models and the Poisson ratio can be obtained, the material property distribution situation in the gradient region can be obtained to conduct detail stress analysis conveniently, and the modeling workload for conducting detail analysis on the gradient region can be greatly reduced.

The invention discloses a model pile body internal force rating device and method. The model pile body internal force rating device comprises a vertical frame, wherein the bottom of the vertical frame is provided with an axial loading device; the axial loading device is provided with a model pile; the middle of the frame is provided with a horizontal loading device; loading sensors are arranged in the axial loading device and the horizontal loading device respectively; the model pile is provided with a strain sensor; the loading sensors and the strain sensor are connected with a control center through a strain collection instrument; the control center is in control connection with the axial loading device. According to the model pile body internal force rating device and method, the accurate axial loading is performed on the model pile through a small hydraulic jack and strain values of different positions of strain pieces of the model pile are measured to obtain the axial force rating coefficient between the strain of every strain piece and the axial force of a corresponding position of pile body; a concentrated load is applied to the middle section of the pile through a pulley and the strain difference of the strain pieces of the section of the model pile is measured to obtain the bending moment rating coefficient of the strain difference of the strain pieces and the bending moment of the section of the pile body; the internal force of the pile body can be accurately determined.

The present invention discloses a strain test method using multiple balance reference points. Multiple measurements are carried out in group i in a certain test period and group j in another test period through a strain sensor, temperature influence functions yiw(s) and yjw(s) of a strain under constant environment humidity, and humidity influence functions yis(w) and yjs(w) of a strain under constant temperature are obtained, and strain values yi(w,s) and yj(w,s) under a specific temperature and humidity can be obtained by conversion. Thus, strain values xigm and xj-n in different working conditions in a same group i and in another different group j under different temperature conditions and humidity conditions are respectively measured, and converted into strain values yigm(w,s) and yj(w,s), strain differences delta y(igm-i)(w,s), delta y(j-i)(w,s), and temperature influence functions delta y(igm-i)w(s) and delta y(j-1)w(s) of the strain differences or humidity influence functions delta y(igm-i)s(w) and delta y(j-i)s(w) under a specific temperature and humidity condition. The strain test method using multiple balance reference points aims to eliminate the influence of environment temperature and humidity on the measurement of the strain of a member, and improve the accuracy of the measurement of the strain.

A method for measuring the actual stress of steel bars in existing reinforced concrete shear walls and columns, to obtain the elastic modulus E and yield strength f of steel bars in non-important parts y and ultimate tensile strength f u ; Chisel off the concrete to expose a section of the steel bar to be tested; grind off the oxide layer on the surface until it is smooth and clean it, and attach four strain gauges in the circumferential direction of the same section; before being cut off, obtain the initial strain ε 30 , ε 40 , ε 50 and ε 60 , and the initial strain value obtained from the mean value after being cut off, respectively to obtain the release strain ε 31 , ε 41 , ε 51 , ε 61 , and the released strain value is obtained from the average value, the strain difference Δε of the steel bar under test before and after being cut; the actual stress value σ is obtained by using the difference between the sum and the value; comparative analysis σ, f y and f u The size relationship of the measured steel bar and determine the stress state at the steel bar under test; reconnect the steel bar under test. The method can effectively detect the actual stress state of the steel bars in the existing reinforced concrete shear walls and columns.

The invention provides a method for measuring the internal force and the deformation of a precast pile. After a piling procedure is accomplished, a sensor and vertical pile foundation static load experiment equipment which is connected with the sensor are installed; before the next stage of load is exerted, the numerical reading of the sensor under one stage of load is recorded, namely, the relative deformation at an observation point (at which a force transmission rope is connected) and a reference part; the relative deformation is divided by the pile length of the section so as to obtain the relative strain of the observation section relative to a reference plane; the strain difference between two sections is obtained through the strains of two adjacent observation sections relative to the reference plane; and the axial force of the pile body at each anchoring head section is calculated according to the elastic modulus calibration result of the pile body concrete. According to the method for measuring the internal force and the deformation of the precast pile provided by the invention, the sensor is installed after the piling procedure is accomplished, so that the sensor is prevented from being damaged in the piling process, and moreover the measurement precision is high, and the cost can be controlled effectively.