Numerical Simulation And Experimental Research On The Mechanical Response Of Lung Tissue Subject To The High Intensity Sound Waves

This research is based on the theory of Helmholtz resonator and combines numerical simulation with experiments to study the mechanical response of lung tissue to the high intensity sound waves.The research constructs a model of human’s lung tissue by means of COMSOL MULTIPHYSICS numerical simulation software.Through the numerical modeling of lung’s response in the sound field,the effect and damage mechanism of intense sound wave to the hollow organs can be figured out.Meanwhile,the experiment of biological effect of intense sound wave is designed and completed.The experiment uses SD rats as the object of study.The acoustic sensor can monitor characters of sound field timely and the high-precision laser displacement sensor is used to measure the displacement of the surface of SD rats.Simulation results show that the model with simple structure and materials such as air and parenchyma is close to the ideal Helmholtz resonator.The resonance frequency can be estimated well through the modified formula of classical lumped parameter system’s resonance frequency.Once taken into account of the elastic wall,models cannot be an isochoric change.The resonance frequency will be different with the change of width of elastic wall or density of parenchyma.For the model considering four different materials including air,elastic wall,parenchyma and bones,there is an evident resonance in 121 Hz.In this frequency,the model absorbs most acoustic energy and gets the biggest displacement of elastic wall.Bones is treated as fixed constraint since their characters are quite different from other structures’.The tissues near bones have fewer displacements than other areas,which causes damage of tissues.Experiments of biological effect show that there is an evident resonance on SD rats’ chest in specific frequencies.Excluding the influence of breath,the displacement can approach to 1mm.Under the experiment condition we designed,the experiment proves the existence of thoracic organs’ resonance caused by intense sound wave in the frequencies of 250 Hz,280Hz,335 Hz and 390 Hz.Furthermore,the resonance is the main reason of organs’ injury.