1、 Program composition The dynamic true triaxial test system is used together with the existing Hopkinson pressure bar test system. The main body includes four parts:
1) true triaxial main engine loading system,
2) axial loading servo hydraulic system,
3) data measurement and acquisition system.
2. True triaxial host loading system
The whole machine is designed with an integrated structure, and the loading frame is forged with high-strength alloy. The loading form is that two oil cylinders are loaded in one direction respectively, and the oil cylinders are installed on two planes perpendicular to the frame. The connection is connected with high-strength bolts, the front end of the piston is connected with the load sensor, and the front end of the load sensor is connected with the adjusting pressure block, as shown in the figure.
Its structure is specific to the high rigidity loading frame, integrated structure design, compact structure. In consideration of the combination with the original Hopkinson bar system, the whole machine is reserved with bolt holes for installing guide rail slide block; the true triaxial system does not include guide device and platform device.
3. Data measurement and acquisition system The true triaxial loading system is composed of three hydraulic control systems: multi-channel acquisition card, hydraulic source, control valve, pressure transmitter, dynamic and static strain sensor, etc.; the measurement of stress and strain is completed by static data acquisition system, and the dynamic stress and strain is completed by existing dynamic strain gauge and data acquisition system. During the test, two strain gauges are attached to three directions at the same time, and static and dynamic data are collected and calculated respectively. The stress part is directly collected by the pressure transmitter.
3.1 function introduction of alt1000 ultra dynamic data acquisition system: Alt1000 ultra dynamic data acquisition system is specially used for the test and analysis of hobkinson bar experiment. The highest transient sampling rate of the system is 1MHz, each channel is independent of a / D analog-to-digital converter, and the external strain conditioner completes the stress-strain test and analysis of 1 / 4 bridge, half bridge and full bridge states. The system has the functions of real-time acquisition, real-time display, real-time storage and real-time analysis of the measured signal, automatic test control and data waveform analysis and processing.
3. Alt1000 dynamic data acquisition system:
The dynamic and static resistance strain gauge is suitable for static and dynamic strain test with frequency lower than 200Hz. At the same time, it can be equipped with different sensors to measure strain, displacement, load, pressure and other physical quantities. The acquisition and analysis software has powerful software analysis functions such as data acquisition, T-Y diagram, X-Y diagram, bar diagram display, strain flower strain analysis, etc. 1.2 performance characteristics
1. Full digital intelligent design, simple operation, rich measurement functions, with hot plug USB computer interface and cascade interface. The dynamic and static resistance strain gauge is connected with the test software to form a virtual instrument test system.
2. Dynamic and static resistance strain gauge is suitable for static and low frequency dynamic strain test.
3. Each measuring point can be bridged separately (1 / 4 bridge, half bridge and full bridge), and the balance mode is automatic scanning balance.
4. At the same time, it can be equipped with different sensors to measure strain, displacement, load, pressure and other physical quantities.
5. The test point switching is completed by the program control of imported vacuum relay to reduce the influence of contact resistance change caused by switch oxidation on the test results.
6. The dynamic and static resistance strain gauge can be used for single machine test or multi machine cascade test, and one computer can control eight of them at the same time Type of instrument to be tested.
7. Configure acquisition and analysis software, which has powerful software analysis functions such as data acquisition, T-Y diagram, X-Y diagram, bar diagram display, strain flower strain analysis, etc. 1.3 technical indicators 1. Main engine measuring point:
8 points;
2. Measurement range: ± 38000 μ ε;
3. Balance range: ± 38000 μ ε;
4. Resolution: strain: 1 μ ε; tensile pressure and displacement: 0.01% / F.S;
5. Bridge Road Resistance: 60 ~ 1K Ω;
6. bridge pressure: DC 2V;
7. Coefficient setting range: 1.00-10.00;
8. Bridge formation: 1 / 4 bridge, half bridge and full bridge;
9. Zero drift: ± 3 μ ε / 4H; ± 1 μ ε / ℃;
10. Nonlinearity: ± 0.02% F.S;
11. Acquisition rate (Hz): 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2500;
12. Working mode: computer external control
13. Display mode: table, graphic display;
14. Acquisition mode: manual acquisition, continuous acquisition, timing acquisition, trigger acquisition;
15. Measuring object: strain gauge; strain displacement, load and pressure sensor;
16. Power supply: AC 220V (± 10%) 50Hz;
17. Computer interface: USB
18. Cascade interface: RS485;
19. Temperature: - 10 ~ + 45 ℃
4. Technical specifications of alt1000 strain adapter:
(1) It can realize the program-controlled switching and self checking function of bridge and road;
(2) Applicable resistance of strain gauge: 50 Ω ～ 10000 Ω;
(3) Bridge supply voltage: 2V, 5V, 10V (optional);
(4) Program controlled bridge way: 1 / 4 bridge (standard 120 Ω), half bridge, full bridge;
(5) Gain: 100 times (30, 50100500100 optional);
(6) Maximum bandwidth: DC ～ 300kHz (+ 0.5dB ~ - 3dB);
(7) Output characteristics: output voltage: 7vrms; output current: 5mA; output resistance: less than 1 Ω;
(8) Size: 30mm (W) × 20mm (H) × 80mm (L) (single channel);
5. Sample fixture system The specimen fixture system can refer to the existing true triaxial fixture system. The loading surface needs to avoid the patch area and lead of dynamic and static strain gauges, so as to avoid affecting the stress collection.
