program thermal_contact_resistance implicit none ! Input variables integer :: material_pair_idx real(8) :: k1, k2, Hc real(8) :: Ra1, Ra2 real(8) :: P integer :: fluid_tim_idx real(8) :: k_tim_input, t_tim_input real(8) :: temp_val real(8) :: area_val, Q_val ! Computed intermediate variables real(8) :: ks, sigma, m1, m2, m, Y, hc_s, kg_air, kg_dry, hc_g_dry real(8) :: h_joint_dry, R_double_prime_dry, R_c_dry, delta_T_dry real(8) :: kg_tim, hc_g_tim, h_joint_tim, R_double_prime_tim, R_c_tim, delta_T_tim real(8) :: k_tim_act, t_tim_act ! Read inputs read *, material_pair_idx if (material_pair_idx == 7) then read *, k1 read *, k2 read *, Hc else if (material_pair_idx == 1) then ! Al-Al k1 = 180.0d0 k2 = 180.0d0 Hc = 950.0d0 else if (material_pair_idx == 2) then ! Cu-Cu k1 = 390.0d0 k2 = 390.0d0 Hc = 700.0d0 else if (material_pair_idx == 3) then ! Steel-Al k1 = 50.0d0 k2 = 180.0d0 Hc = 950.0d0 else if (material_pair_idx == 4) then ! Steel-Steel k1 = 50.0d0 k2 = 50.0d0 Hc = 1500.0d0 else if (material_pair_idx == 5) then ! SS-SS k1 = 15.0d0 k2 = 15.0d0 Hc = 2900.0d0 else if (material_pair_idx == 6) then ! Cu-Al k1 = 390.0d0 k2 = 180.0d0 Hc = 700.0d0 end if read *, Ra1 read *, Ra2 read *, P read *, fluid_tim_idx read *, k_tim_input read *, t_tim_input read *, temp_val read *, area_val read *, Q_val ! 1. Harmonic thermal conductivity ks = 2.0d0 * k1 * k2 / (k1 + k2) ! 2. Surface roughness (Ra1, Ra2 in microns) sigma = sqrt(Ra1**2 + Ra2**2) ! 3. Surface slopes (m1, m2 from Lambert & Fletcher relation) m1 = 0.076d0 * (Ra1**0.52d0) m2 = 0.076d0 * (Ra2**0.52d0) m = sqrt(m1**2 + m2**2) ! 4. Solid contact conductance (hc_s in W/m2.K) ! hc_s = 1.25 * ks * (m / (sigma * 10^-6)) * (P / Hc)^0.95 hc_s = 1.25d0 * ks * (m / (sigma * 1.0d-6)) * ((P / Hc)**0.95d0) ! 5. Mean gap separation (Y in microns) ! Y = 1.53 * sigma * (P / Hc)^-0.097 Y = 1.53d0 * sigma * ((P / Hc)**(-0.097d0)) ! 6. Dry contact computations (Reference for comparison, or if selected) ! gas conductivity for air as a function of temperature: k_air = 0.0243 + 7.1e-5 * T kg_air = 0.0243d0 + 7.1d-5 * temp_val ! Determine gas conductivity for dry reference: Air or Vacuum if (fluid_tim_idx == 2) then kg_dry = 0.0d0 ! Vacuum else kg_dry = kg_air ! Air (default dry reference) end if hc_g_dry = kg_dry / (Y * 1.0d-6) h_joint_dry = hc_s + hc_g_dry R_double_prime_dry = 1.0d0 / h_joint_dry ! Area-based resistance (area is in cm2, convert to m2) R_c_dry = R_double_prime_dry / (area_val * 1.0d-4) delta_T_dry = Q_val * R_c_dry ! 7. Actual configuration computations (TIM or Dry) if (fluid_tim_idx == 1) then ! Air (Dry Air) h_joint_tim = h_joint_dry R_double_prime_tim = R_double_prime_dry k_tim_act = kg_air t_tim_act = Y else if (fluid_tim_idx == 2) then ! Vacuum (Dry Vacuum) kg_dry = 0.0d0 h_joint_tim = hc_s R_double_prime_tim = 1.0d0 / hc_s k_tim_act = 0.0d0 t_tim_act = Y else ! Thermal Grease or Pad k_tim_act = k_tim_input t_tim_act = t_tim_input ! unified TIM model if (t_tim_act > Y) then R_double_prime_tim = ((t_tim_act - Y) * 1.0d-6) / k_tim_act + & 1.0d0 / (hc_s + k_tim_act / (Y * 1.0d-6)) else R_double_prime_tim = 1.0d0 / (hc_s + k_tim_act / (Y * 1.0d-6)) end if h_joint_tim = 1.0d0 / R_double_prime_tim end if R_c_tim = R_double_prime_tim / (area_val * 1.0d-4) delta_T_tim = Q_val * R_c_tim ! Print detailed results report print *, '==================================================' print *, ' THERMAL CONTACT RESISTANCE CALCULATION REPORT' print *, '==================================================' print *, '' print *, 'INPUT CHARACTERISTICS:' print *, '--------------------------------------------------' print '(A,F10.2,A,F10.2,A)', ' Material Conductivities (k1, k2): ', k1, ' / ', k2, ' W/(m.K)' print '(A,F10.2,A)', ' Harmonic Mean Conductivity (k_s): ', ks, ' W/(m.K)' print '(A,F10.2,A)', ' Microhardness Softer Solid (H_c): ', Hc, ' MPa' print '(A,F10.3,A,F10.3,A)', ' Surface Roughnesses (Ra1, Ra2): ', Ra1, ' / ', Ra2, ' um' print '(A,F10.3,A)', ' Effective Roughness (sigma): ', sigma, ' um' print '(A,F10.4,A,F10.4,A)', ' Profile Slopes (m1, m2): ', m1, ' / ', m2, ' rad' print '(A,F10.4,A)', ' Effective Interface Slope (m): ', m, ' rad' print '(A,F10.3,A)', ' Apparent Contact Pressure (P): ', P, ' MPa' print '(A,F10.3,A)', ' Force Ratio (P/H_c): ', P/Hc, ' ' print '(A,F10.2,A)', ' Contact Temperature: ', temp_val, ' C' print '(A,F10.2,A)', ' Contact Area: ', area_val, ' cm2' print '(A,F10.2,A)', ' Dissipated Heat Power (Q): ', Q_val, ' W' print *, '' print *, 'INTERFACE MICRO-GEOMETRY:' print *, '--------------------------------------------------' print '(A,F10.4,A)', ' Mean Separation Gap (Y): ', Y, ' um' print '(A,ES12.4,A)', ' Solid-Solid Spot Conductance (hc_s):', hc_s, ' W/(m2.K)' print *, '' print *, 'THERMAL PERFORMANCE COMPARISON (DRY VS TIM):' print *, '--------------------------------------------------' print *, '1. DRY CONTACT REFERENCE (AIR INTERFACE)' print '(A,ES12.4,A)', ' Gas Conductivity (k_air): ', kg_air, ' W/(m.K)' print '(A,ES12.4,A)', ' Gas Gap Conductance (hc_g_dry): ', hc_g_dry, ' W/(m2.K)' print '(A,ES12.4,A)', ' Total Dry Conductance (h_c): ', h_joint_dry, ' W/(m2.K)' print '(A,ES12.4,A)', ' Contact Resistance (R"_c, dry): ', R_double_prime_dry, ' m2.K/W' print '(A,F12.4,A)', ' Joint Resistance (R_c, dry): ', R_c_dry, ' C/W' print '(A,F10.2,A)', ' Interface Temp Drop (delta_T): ', delta_T_dry, ' C' print *, '' print *, '2. ACTUAL CONTACT CONFIGURATION' if (fluid_tim_idx == 1) then print *, ' Mode: Dry Air' else if (fluid_tim_idx == 2) then print *, ' Mode: Dry Vacuum' else if (fluid_tim_idx == 3) then print *, ' Mode: Thermal Grease' print '(A,F10.3,A)', ' TIM Conductivity (k_TIM): ', k_tim_act, ' W/(m.K)' print '(A,F10.2,A)', ' TIM Bond Thickness (t_TIM): ', t_tim_act, ' um' else if (fluid_tim_idx == 4) then print *, ' Mode: Thermal Pad' print '(A,F10.3,A)', ' TIM Conductivity (k_TIM): ', k_tim_act, ' W/(m.K)' print '(A,F10.2,A)', ' TIM Thickness (t_TIM): ', t_tim_act, ' um' end if print '(A,ES12.4,A)', ' Total Active Conductance (h_c): ', h_joint_tim, ' W/(m2.K)' print '(A,ES12.4,A)', ' Contact Resistance (R"_c, tim): ', R_double_prime_tim, ' m2.K/W' print '(A,F12.4,A)', ' Joint Resistance (R_c, tim): ', R_c_tim, ' C/W' print '(A,F10.2,A)', ' Interface Temp Drop (delta_T): ', delta_T_tim, ' C' print *, '' print *, 'SUMMARY COMPARISON INDICATORS:' print *, '--------------------------------------------------' print '(A,F10.2,A)', ' TIM Resistance Reduction Factor: ', R_double_prime_dry / R_double_prime_tim, ' x' print '(A,F10.2,A)', ' TIM Temperature Drop Reduction: ', (delta_T_dry - delta_T_tim), ' C' print *, '==================================================' end program thermal_contact_resistance