Method for predicting volume change of void generated in resin filled in porous body, and method for analyzing flow of resin material in porous body

A method for predicting volume change of void in a resin material or a resin material filled in a porous body arranged in contact with a solid member, the void being a space in the resin material formed by gas generated from the solid member during rising of temperature, the method comprising:

• (a) taking in a configuration of the porous body in which the resin material is filled, a special configuration in which the resin material is filled in contact with the porous body, and data regarding the solid member in contact with a flow region of the resin from a storage device to a computing device, and performing a dissolving process for dissolving the same into three-dimensional solid elements based on the data;
• (b) entering properties including at least a density, a thermal conductivity, a specific heat and a viscosity of the resin material, an aperture ratio of the porous body, across-sectional specific resistance of the porous body, a density, a specific heat and a thermal conductivity of the porous body, and boundary conditions comprising an initial temperature of the solid member and the resin material, and a temperature change of the solid member;
• (c) entering a time variation of volume of a single gas or a total value of volume of a plurality of gases and a specific heat of the single or the plurality of gases generated from the solid member, the porous body or the resin material in response to the temperature change of the solid member, the porous body or the resin material;
• (d) computing an equation of continuity, a Navier-Stokes equation and an energy conservation equation based on the three-dimensional solid elements to thereby calculate the change of resin temperature, calculate the change of viscosity accompanying the change of temperature of the resin material, calculate a function including the cross-sectional specific resistance and the viscosity as a flow resistance factor of the porous body, and enter to the Navier-Stokes equation a product of the flow resistance factor of the porous body and the flow rate and density of the resin as an external force per unit volume of the porous body via fluid resistance;
• (e) entering a change in number of moles of the gas generated from the solid member, the porous body or the resin material, an initial void dimension, an initial time increment regarding an analysis of a flow process of the resin, and calculating the equation of continuity, the Navier-Stokes equation and the energy conservation equation based on the three-dimensional solid elements to thereby compute the flow of the resin material and the void by the generation of gas;
• (f) in the initial time increment of resin flow analysis (first step),
• computing an initial number of gas moles n0 based on state equation (2) when t0 represents initial time, Δt1=t1−t0 represents time increment, an initial void is set having a pressure P0, a volume V0 and a temperature T0 at initial time t0, and wherein R represents gas constant and n represents number of gas moles;
• PV=nRT (2)
• calculating the initial number of gas moles n0 using equation (2), wherein γ represents specific heat ratio of the generated gas,
• calculating a number of gas moles n1 based on the entered time variation of the number of gas moles generated from the solid member during initial time increment t=t0 to t1,
• calculating a void inner pressure P1 using equation (2) varied via rising of temperature and increased number of moles when void volume is not varied from V0 at t=t0 to t1, when assuming that the resin temperature has an average temperature T1 (constant) and the void temperature is equal to the resin temperature during the initial time increment,
• calculating via fluid analysis the void pressure and void volume P1′ and V1 at t=t1 using said equation (1) using the average temperature T1 (constant) at t=t0 to t1;
• (g) in a subsequent time increment (second step),
• calculating a number of moles n2 generated during the time region based on the entered time change of the number of moles of the gas generated from the solid member when the time increment is Δt2=t2−t1, wherein based on step 1, the pressure at t=t1 is P1′, the volume is V1, and at t=t1 to t2, the void volume is V1 (constant) from t1,
• calculating based on equation (2) a void inner pressure P2 at t=t1 to t2 varied by the rising of temperature and the increase of number of gas moles when the void volume is not varied from V1 and using an average temperature T2 (constant),
• computing a void pressure and a void volume P2′ and V2 via fluid analysis at t=t2 using the equation (1) during t=t1 to t2;
• and
• (h) repeating the calculation having added the time increment until the time reaches a predetermined time and thereby calculating the change in void volume at least due to the generation of gas.