A procedure is proposed to evaluate the reliability of antenna deployment mechanism (ADM) which is a key technology in large satellite antenna development. Because of lack in basic reliability data on space mechanical components, a realistic evaluation procedure needs careful selection of test items for cost and time saving. The Failure Mode and Effects Analysis (FMEA) is conducted to identify all possible failure modes, among which the critical modes are selected for further investigations. The bearing performance and friction are found to be critical, and detailed tests are performed. The test results show that the deployment and friction torque distributions can be assumed as normal distributions. The deployment reliability of the ADM was calculated based on these distributions. This paper also describes the method to prevent the failure derived from the reduction in bearing clearance.
The thermal analysis method for the heat pipe embedded equipment panel of communications satellite is presented. The analytical model of the honeycomb sandwich panel embedded with heat pipes is developed and evaluated by the experiments. The new method to predict temperature distribution of the entire communications equipment panel precisely without the increase of computer CPU memory size is proposed. It works even when the large number of communications transponders are put on the panel. The correctness of the method is also confirmed by the experiment.
An in-service flaw detection and estimation method for CFRP composites using electrical potential drop is developed. It involves passing a constant current through composites and measuring the electrical potential, which changes as the crack advances. The resister network analysis of the random lattice model of CFRP composites shows that even in the plane normal to the fiber direction, CFRP composites can be considered as electrically homogeneous on a gross scale, i. e., on a scale of dimensions dozens of times large compared with the fibre radius. The analysis also shows that the method can detect the small increment of crack growth in CFRP composites with only a fraction of current that is required for metals. The relation between the amount of the crack growth and the potential change is expressed by a broken line composed of two straight lines. The method is applied to the delamination test of the DCB composite laminate specimen and the results are compared with the FEM solutions. The present method can provide accurate and inexpensive means for flaw detection and crack growth measurement in CFRP composite structures.
Consideration of inertia effect is important to estimate the stress intensity factor for impact fracture toughness test. In the present paper the dynamic stress intensity factor K(t) is calculated from K(t)=α(t)·Kstat, where α(t) is the impact response function and Kstat is the corresponding static value. The α(t) is computed by superimposing the step response function h(t). The h(t) for the crack, subjected to step load, is evaluated using the finite element method. The numerical computation of K(t) is carried out for the experiment introduced by Costin et al. The results indicate the good applicability of this method for the determination of the impact fracture toughness K1d.