Research On Rigid Impact Protection Device Of Hydraulic Power Load Test Machine

During the process of impact test,the hydraulic dynamic loading impact test device releases huge energy in a very short time to form high-pressure,which forms the impact effect of high speed stamping.There are many uncertain factors in the impact test,such as the fracture of the experimental component or the accident of the experimental component from the test-bed.The cylinder piston pole of impact will directly impact the base,resulting in rigid impact of the test machine and causing accidents.Aiming at the impact process of hydraulic dynamic loading testing machine,taking the rigid impact process of impact cylinder as the research object,through the numerical analysis and numerical simulation of impact dynamics and explicit dynamics,the wave equation of emulsion and piston rod of impact cylinder in the rigid impact process was established.Numerical analysis and numerical simulation were carried out for the effect of pre-folded energy absorbing box on rigid impact.The cushioning effect of 8 mm pre-folded energy absorbing box under the impact load of 1500 KN,2500 KN,3500 KN,4500 KN,5500 KN and 6500 KN was analyzed.The prefolded energy absorbing boxes with 14 mm,15mm and 16 mm thickness were compared and analyzed,which showed that 15 mm pre-folded energy absorbing box was suitable for 6500 KN hydraulic dynamic loading testing machine.The LS-DYNA fluid-solid coupling method was used to dynamic analysis of protection effect of rigid impact protection device,and the influence of prefolded energy absorbing box on the cushioning effect of the rigid impact protection device was explored.The dynamic load coefficient of the buffer cylinder was deduced by energy method,and the dynamic analysis of the impact process of the buffer cylinder was carried out by using the twoway fluid-solid coupling method.-*The results shows that in the process of rigid impact of impact cylinder the reflection of stress wave and the vibration of piston rod will increase the impact force and cause destructive accidents.The plastic deformation of the pre-folded energy absorbing box makes the compression wave of the piston rod of the impact cylinder transmit in the form of plastic wave,changing the rigid impact into the soft impact.Different impact loads have great influence on the cushioning effect of the pre-folded energy absorbing box.The 6500 KN hydraulic dynamic loading testing machine is suitable for the 15 mm pre-folded energy absorbing box.The anti rigid impact protection device can effectively protect the hydraulic dynamic loading testing machine.The prefolded energy absorbing box plays the main role in the early stage,and the buffer cylinder continues to protect the testing machine after the pre-folded energy absorbing box is fully buckled.When the buffer cylinder is impacted,the equivalent stress at the interface between the middle layer of the cylinder wall and the safety valve is large,and the piston rod of the buffer cylinder moves in a fluctuating manner,which leads to the fluctuating change of the emulsion pressure in the buffer cylinder.In the process of the emulsion pressure increasing,the pressure is transmitted by layers,the pressure at the interface of the safety valve increases slowly,the emulsion can not flow out in time,and the emulsion pressure decreases,The overall pressure drop is fast,and the pressure drop at the safety valve interface is slow.There are 70 pictures,1 table and 51 references in this paper.