Support optimization tool for aero engine configuration systems

In an aircraft engine, basic functionality of configuration system is to form the network of supply lines for air, fuel & oil. Configuration hardware mainly consists of tubes, ducts, valves & support brackets. Many of the Aircraft engines are failed due to failure of fuel pipes and caused big hazards. Hence to avoid accidents, hard wares are designed properly against the failures. In order to use the resources properly optimum design of hard wares is necessary. The two basic design requirements for configuration systems are: (a) high cycle fatigue (vibratory stresses) and (b) low cycle fatigue (thermally induced stresses). Under these design requirements optimum design can be done through the selection of critical design parameters. Critical design parameters in a configuration system considered in the present study are: (i) Support location for the tube layout and (ii) Bracket support type at this location. The judicious selections of these two design parameters greatly influence the high cycle fatigue and low cycle fatigue life. This also helps in reducing the weight and cost of the system. Design optimisation is an iterative process and computer software can help to obtain an optimum design. In the present study, user friendly software is developed using TCL/TK environment. This is linked with a commercial software ANSYS and PEZ tool. ANSYS is used to carry out the structural analysis considering preliminary support locations. Analysis results from ANSYS are the inputs for the optimization analysis. PEZ tool modifies the support locations based on the optimization results. ANSYS will analyse the structure once again based on the modified support locations. This loop will continue till target reaches

Reliability Based Seismic Design of Open Ground Storey Framed Buildings

Open Ground Storey (OGS) framed buildings in which the ground storey is kept open without providing any infill walls and mainly used for parking, are increasingly common in urban areas. Vulnerability of this type of buildings has been exposed in the past earthquakes. OGS buildings are conventionally designed considering a bare frame analysis, ignoring the stiffness of the infill walls present in the upper storeys, which under-estimates the inter-storey drift and the force demand in the ground storey columns. To compensate this, a multiplication factor (MF) is introduced by various international codes while calculating the design forces (bending moments and shear forces) in the ground storey columns. Present study focuses on the evaluation of seismic performances of OGS buildings designed with alternative MFs through performance-based design approach using a probabilistic framework. The probabilistic seismic demand models and corresponding fragility curves for all the selected OGS buildings are developed for different performance levels. Reliability curves are developed for the OGS building frames against the seismic hazard associated with maximum seismic zone of India (Zone-V of IS 1893, 2002). Similar analyses are also carried out on bare frames and fully infilled frames for reference. It is found from the present study that the application of MF only in ground storey, as suggested by many literatures and design codes (including Indian standards), is not an appropriate solution for design of OGS buildings as it leads to vulnerable adjacent storey. This study proposes an effective scheme of MF for design of OGS buildings that yields acceptable levels of reliability index