| At present,many commercial products in China are still over-packaged,but the per capita resources in China are very poor,it is impossible to go on like this for a long time.Under the background of sustainable development put forward by the central government,reasonable packaging has become the general trend.However,a large part of packaging damage is due to random vibration during transportation.In this paper,a three-degree-of-freedom(dof)semi-positive definite system is taken as the prototype,and a dynamic model of the three-degree-of-freedom semi-positive definite system is established.In addition,the dynamic response of the packaging system under random vibration is analyzed in the form of MATLAB simulation system and experiment,which provides some guidance for the protection of the packaging system.The main contents of this paper are as follows:First of all,combined with the real transportation environment,the use of MATLAB to prepare M file,using the time domain randomization method into the time domain signal;The characteristic parameters of the three-degree-of-freedom semi-positive definite system are obtained through experiments.The random vibration simulation model of the three-degree-of-freedom semi-positive definite system was established according to the dynamics equations of the three-degree-of-freedom semi-positive definite system.The ASTM-d4728 vibration power spectrum of truck transportation was used as the excitation.And at low frequency and high frequency of two frequency range compared to discuss the differences of the results of experiment and simulation,the results showed that three degrees of freedom positive semi-definite random vibration simulation model(low frequency)simulation with maximum power spectral density value with(low frequency)is one of the most high power spectral density values,the relative error is 9.93%between the engineering standards.In addition,the relative error between the resonance frequency isolated from the spectral analysis and the experimental results is only 10.2%,which belongs to the normal category.Due to the sharp decrease of energy in the high frequency band,the spectral density analysis is distorted,which leads to the fact that the vibration intensity characterization in the random vibration test is 25%higher than that in the simulation.Finally,the influence of RMS value,mass,stiffness and damping on the random vibration response of three-degree-of-freedom semi-definite system is discussed by using the simulation model.Based on the above analysis,it can be seen that the simulation model of random vibration of three-degree-of-freedom(dof)semi-positive definite system has a good reducibility in the low-frequency section,while the power spectrum in the high-frequency section is seriously distorted.Therefore,this simulation model can be further used to study the influences of RMS,mass,damping and elasticity coefficients on random vibration response of packaging in low frequency band,so as to help product developers develop and design more suitable structural parameters. |
