Finite Element Analysis Of Geoacoustic Sensors Under Seafloor Environmental Loads

Earthquakes,as a natural disaster that poses a serious threat to the lives and property of people around the world,always require relevant seismic detection sensors to monitor their occurrence information in real time in order to gain more refuge time.Most of the earthquakes occurred in the ocean and were placed on the ocean floor.Seismic sensors will be affected by complex ocean floor environmental loads such as wave forces,ocean currents,and seismic waves,resulting in inaccurate sensor monitoring and even affecting working life.In order to accurately study the structural dynamic response of the geoacoustic sensor under the subsea environmental load,this paper selects the ANSYS Workbench finite element simulation platform,and used the fluid-structure coupling module,modal analysis module and transient analysis module to detect the acoustic sensor under wave,and ocean current,and the structural response of the submarine environmental load such as seismic waves is studied and analyzed.The main work of this paper will be carried out in the following aspects:1.Use the water particle wave method to control the percentage of the fluid volume in the total volume of the water tank in the two-phase flow model and define the velocity related to the position and time of the inlet boundary conditions by compiling the corresponding UDF macro program,so as to simulate Stowe the third-order wave and the attenuation of the porous medium at the exit boundary,and create a two-dimensional numerical wave flume.2.Choose different lengths of wave-cutting regions,and select the optimal wave-cutting region lengths by comparing and analyzing the four wave surface equations.The numerical simulation of Stokes third order wave and theoretical wave are compared and analyzed from three aspects of wave surface equation curve,wave time history curve and period of different points respectively.3.Use computational fluid dynamics software FLUENT to compile a UDF macro program based on the parameters of the third-order wave and sixth-order wave of Stokes and generate a numerical wave flume,a flow field model of geoacoustic sensors placed at different water depths is established,and waves and ocean currents are applied.The pressure load on the sensor surface is imported into the solid field for calculation by a unidirectional fluid-solid coupling method.Then,the observation and analysis of the equivalent stress and the total displacement cloud image characteristics and the change trend of the geoacoustic sensor at different water depths are performed.4.Use the Morison formula method to calculate the wet modal vibration characteristics and seismic response of the ground acoustic sensor structure through the modal analysis and transient analysis modules of the ANSYS Workbench platform,and compare with the dynamic characteristics and dynamic response of the structure in the absence of water after analysis at the same time.It is found that the natural frequency of the wet mode is lower than the natural frequency of the dry mode after the ground acoustic sensor is placed on the ocean floor,and the structural response caused by the seismic load is greater than that when there is no water,indicating that the presence of water makes the ground acoustic sensors are more vulnerable to instability under earthquakes,amplifying the effect of external loads on their structure.