Prediction of pressure drop in fluid tuned mounts using analytical and computational techniques

A simplified model for predicting pressure drop in fluid tuned isolator mounts was developed. The model is based on an exact solution to the Navier-Stokes equations and was made more general through the use of empirical coefficients. The values of these coefficients were determined by numerical simulation of the flow using the commercial computational fluid dynamics (CFD) package FIDAP

THERMAL RELIABILITY DESIGN AND OPTIMIZATION FOR MULTILAYER COMPOSITE ELECTRONIC BOARDS

ABSTRACT Boards made of composites are susceptible of structural failure or irreversible damage under thermally raised stresses. A thermal/structural finite element model is integrated in this study to enable the predictions of the temperature and stress distribution of vertically clamped parallel circuit boards that include series of symmetrically mounted heated electronic modules (chips). The board is modeled as a thin plate containing four heated flush rectangular areas that represent the electronic modules. The finite element model should be to able to accept the convection heat transfer on the board surface, heat generation in the modules, and directional conduction inside the board. A detailed 3-D CFD model is incorporated to predict the conjugate heat transfer coefficients that strongly affect the temperature distribution in the board and modules. Structural analyses are performed by a FE model that uses the heat transfer coefficients mentioned above, and structural elements capable of handling orthotropic material properties. The stress fields are obtained and studied for the models possessing two and there laminates with different fiber orientations, and interfiber angles. Appreciable differences in values of max stress intensity were observed as the fiber orientation and inter-fiber angle changed. The angular parameters in this study were guided by experimental design (DOE) concepts leading to a metamodel of the stress intensity in the board. The optimum design variables found by the equations of the metamodel. INTRODUCTION Current interest in the thermal analysis of electronic circuit boards arises mainly because of the failure of such components as a result of thermal fatigue. The cooling of the component boards in many applications is the result of the forced or mixed convection air flow. Many studies in the area of convection cooling of boards have been done in the literature but few studies have related the flow field to the structural integrity of the boards. The initial phase of evaluation of stresses involves the understanding of mixed convection flows that removes heat from the boards. A detailed description of steady state and transient mixed convection studies can be found in previous work such as [1 -3]. In one of these studie

MULTI-FIELD FE MODELING OF RESISTIVE HEATING IN A 6061-T6511 ALUMINUM SPECIMEN

ABSTRACT Electric current's effect on material mechanical properties has been of interest since it can lessen the mechanical energy associated with deforming/working a material. The objective of this work is to have a representative model of the thermal/structural effects of electricity on a tensile specimen so that the simple effect of temperature can be separated from any mechanical material property changes due to the electric current. The finite element models in this study were generated and their results were compared to experimental data obtained from a representative tensile test. Comparison with the experimental results on material engineering stress-strain curves and transient temperature profiles offers assurance for the further use of FEA as a significant tool in understanding the electrical effects on material properties. A multi-field large deformation finite element model for a cylindrical tensile bar of 6061-T6511 aluminum is developed to evaluate the distribution of temperature within the specimen. The model also evaluates the stress-strain characteristics of the material while the specimen is carrying a large DC current and being deformed. The simulation results are compared to surface infrared temperature measurements in order to verify the FE model first and then to attain more qualitative and possibly quantitative insight into the effects of electric field