| Ceramic structures are sometimes used in the construction of ships,such as the shields used to search for radars in cruiser superstructures.Ceramic materials have the structural properties of different modulus in tension and compression(hereinafter referred to as bi-modulus).Therefore,the analysis of such materials cannot be carried out by the classical method,and the influence of the bi-inodulus must be considered.Otherwise,errors will be caused.In this paper,a new method for analyzing bi-modulus materials is proposed.The by-modulus ceramic shields are analyzed and studied,and the errors caused by the classical analysis method and the results of considering the bi-modulus properties are observed.The main research contents are as follows:1)For the structural characteristics of materials with bi-modulus properties,it was proposed to judge the tensile and compressive regions of the material by using the first stress invariant as the standard.The APDL language was used in the ANSYS commercial finite element software for secondary development and dynamic analysis module for bi-modulus materials was obtained.2)The accuracy of the developed dynamic characteristic analysis module was verified by using a two-dimensional plane beam with bi-modulus structure properties as the research object.The natural frequencies of the beam were calculated,and results were compared with the counterpart calculated by analytical formula of the bi-modulus beam in the previous literature.The errors obtained were basically below 5%,which indicates the accuracy of the developed module.The vibration mode and material property distribution maps could also be obtained through this module.By comparing the obtained vibration mode with the cocunterpart calculated by the single-modulus vibration mode analytical expression,it was found that the bi-modulus property does not affect the vibration mode of the beam.Through the material property distribution map,the tension and compression partition of the material can be visually seen.3)Since the dynamic characteristic analysis module does not have the function of analyzing the harmonic response and dynamic stress of the material,a method of equivalent proxy model was proposed.Taking the natural frequency as the equivalent criterion,the model of the bi-modulus was equivalent to the single-modulus model through parameter optimization,and the harmonic response of the equivalent proxy model was analyzed in the finite element software to obtain the frequency response curve and dynamic stress.The dyntunic results were compared with the counterpart without considering the double modulus,and the error between the two exceeded 60%.4)By using the two-dimensional bi-modulus plane beam as an example,the feasibility of combining the dynamic characteristics analysis module and parameter optimization to analyze the bi-modulus material was demonstrated.Therefore,the ceramic shield of the ship superstructure was analyzed and studied.The natural frequency,vibration mode and material property distribution maps of different thickness shields were obtained by the dynamic characteristic analysis module.By comparing the obtained vibration mode with the counterpart calculated by analytic formula,it was shown that the bi-modulus property does not a0bect the vibration mode of the plate;by analyzing the material property distribution maps of the bi-modulus plate,it is found that the neutral layer of the bi-modul-us plate is a curved surface rather than a plane.Using the parameter optimization method to obtain the equivalent single-lodulus shield,the equivalent model was used to carry out the next harmonic response analysis to obtain the displacement-frequency curve. |
