| Explosion shock wave is one of the main causes of damage.The load of explosion shock wave in semi-confined environment is very different from that in free environment.Due to the narrow and complex interior environment of cabin,building and other semi-confined Spaces,there will be complex reflection and interference superposition in shock wave collection,which makes it difficult to evaluate the explosion damage in this space.In this paper,the shockwave testing structure and multi-channel micro shockwave data acquisition device are developed.A cushioning structure is designed to eliminate the impact of high impact on shock wave testing,and the finite element simulation is carried out to verify the cushioning effect.It provides a reference design for further study of blast wave test and power evaluation in closed environment.The main work is as follows:First of all,there are some problems in the shockwave lead-type multi-point test method,such as easy damage of cable,long distribution period and large equipment volume.A micro shockwave data acquisition device adapted to the harsh environment of explosion field was designed.It has 15 channels of parallel data acquisition,and the sampling frequency of each channel is adjustable.The maximum sampling frequency of a single channel is 1MHz.Storage capacity up to 32GB;Advantages of 8 retriggers.Xilinx company's FPGA XC6SLX45 is used as the main control core of the device,which completes all the control logic.Through the method of cyclic storage of data before triggering in DDR3 and sequential writing of data after triggering to e MMC,the problem of frequent erasure affecting the life of data collected at high speed to e MMC is avoided.The chip adopts BGA package,which greatly reduces the overall size of the circuit board.The external size of the circuit is 65mm×65mm×50mm.The device realizes high sampling frequency,large capacity,small volume,synchronous acquisition,and can meet the requirements of multi-point shock wave testing in semi-closed environment.Secondly,aiming at the problem that the shock wave pressure test device is seriously interfered with the test data by the impact of high-speed fragments,this paper designs a cushioning structure that soft connects the sensor and the test device shell.In order to solve the problem of measurement error caused by excessive deformation of elastic materials subjected to shock wave pressure,a method of applying pre-pressure to buffer structure was proposed.The finite element analysis method is used to analyze the vibration reduction effect.The0.58 mpa preload is applied to the structure,and the fragment with the speed of 500m/s to2000m/s is used to impact the structure.The simulation results show that the installation design structure can attenuate the stress to 19.02% before installation,and the acceleration to 9.9%before installation.The effectiveness of the buffer structure is verified.Finally,in order to further study the reliability of shock wave testing structure and multichannel micro shock wave data acquisition device.The finite element model of semi-closed environment explosion was established,and different observation points were set up to simulate shock wave overpressure.Through field experiment and simulation data,the pressure distribution of shock wave testing structure in shock wave field is analyzed.The polynomial fitting method was used to fit the formula of different measuring points,and the fitting formula was compared with the experimental results.The error of the explosion facing surface was13.07%,and the error of the side was 5.86%.The characteristics of the first three overpressure curves and the variation rule of the overpressure peak at each measuring point of shock wave are studied. |
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