Dynamic testing system for two-point bending of trapezoidal beams

Dynamic testing system for two-point bending of trapezoidal beams

complete setDynamic testing system for two-point bending of trapezoidal beamsIncluding: test host, controller and software, environmental box, and specimen preparation tools. The test host can test two specimens at a time, which are vertically fixed on the base. A motor-driven loading device is placed at the center of the two specimens. When the motor rotates at a constant speed, the loading device applies a horizontal load to the two specimens, causing them to produce a sinusoidal reciprocating motion. Throughout the entire experimental process, the reciprocating motion of the specimen remains constant (constant strain). As the material properties deteriorate (modulus decreases), the force required to maintain the reciprocating motion of the specimen also decreases. By continuously collecting strain and stress data throughout the entire experimental process, the modulus of the material is calculated, and the fatigue life of the material is predicted according to the criteria for fatigue failure.

Normally, manufacturers recommend that users purchase environmental enclosures that meet regulatory requirements locally. The two main purposes of the two-point bending test based on trapezoidal beams are to test the dynamic modulus of asphalt mixtures (or determine the main curve of dynamic modulus), or to test the fatigue performance of asphalt mixtures (fatigue equation). Users need to consider the following factors:

-If measuring the main curve of dynamic modulus, the temperature coverage range can consider covering the local temperature range of the project. The typical temperature conditions recommended by EU regulations are: -30 ℃, -20 ℃, -10 ℃, 0 ℃,+10 ℃,+15 ℃,+20 ℃,+30 ℃, and+40 ℃. The recommended temperature interval is 10 ℃, and the modulus at 15 ℃ is tested because the indicators specified in the EU material performance standards are all tested at 15 ℃ @ 10Hz.

-If it is to determine fatigue performance, it is generally only tested under normal temperature conditions. Taking EU regulations as an example, the usual required test conditions are 10 ℃ @ 25Hz.

-Throughout the entire testing process, the environmental chamber was able to maintain the temperature near the specimen within ± 1 ℃.

Technical Specifications

sensor

Displacement measurement: range ± 1mm, resolution 0.1 μ m

Load measurement: range ± 5kN, resolution 50N

Temperature measurement: Pt100 platinum resistance probe

Test host

Test frequency range: 1Hz~40Hz

Number of test pieces: 2

Displacement range: maximum 2mm (peak to peak amplitude)

Dimensions: Width 770mm x Depth 440mm x Height 960mm

Weight: 200kg

Power supply: 230V, single-phase, operating frequency 6-220Hz, power 0.9kw

Electrical Control Cabinet

Dimensions: Width 650mm x Depth 650mm x Height 2000mm

Weight: 150kg

In the modulus test method and fatigue test method of two-point bending test for trapezoidal beams, the geometric dimensions of the specimen are required for calculation. Considering the inevitable errors in laboratory processing of specimens, accurate measurement of the geometric dimensions of the specimens becomes essential. Considering that the geometric shape of trapezoidal beams is not suitable for measurement using general vernier calipers or rulers, the manufacturer has specially designed a set of specialized measuring tools including three digital dial gauges. Through this tool, users can easily complete the measurement of specimen dimensions.

Before installing the trapezoidal beam specimen onto the testing host, two metal blocks need to be pasted on its upper and lower end faces. These two metal blocks can be connected and fixed to the reserved testing positions on the host. During the pasting process, it is important to ensure that the upper and lower metal blocks are aligned and parallel to prevent the test specimen from being subjected to loads that are not on a horizontal line, resulting in biased loads and incorrect test results. For this purpose, the manufacturer has specially designed a dedicated specimen installation tool, which allows users to paste 4 specimens at once and ensure that the installation quality meets the testing requirements.

Before the fatigue test, users can set the frequency, temperature, and test termination conditions, which are the percentage of initial modulus attenuation. During the experiment, the software can display the test curves of two specimens in real time, making it easy for users to observe whether the experiment is normal and the progress of the experiment.

After completing fatigue tests at different strain levels, the testing software can automatically fit the fatigue equation (Fatigue Line) based on the complex modulus test results corresponding to each frequency, and obtain the evaluation index of fatigue performance ε 6 (10 ℃ @ 25Hz). Through this feature, the workload of data processing for testers has been greatly reduced. For users engaged in scientific research, the experimental results can be exported in. txt format, supporting users to use other software and computing programs for data analysis.

After completing the modulus test, the software can display the modulus and phase angle of each specimen in the form of a list for each temperature and frequency condition. Users can also display and compare all test results in the modulus frequency coordinate system, making it easier for them to observe and compare the modulus curves of different materials under different temperature conditions.