Surface Crack Growth Propagation
In Damage Tolerance approach, “tolerance” of a component with “damage” for carrying design/operational loads is assessed. Since an existing damage increases with the use, this assessment has to be carried out periodically. To set the periodicity of assessment, good understanding of how the damage grows with load cycles is essential. Simulations provide an alternative to testing, to develop this understanding for complex designs.
The aim of this project was to assess the capabilities of commercially available finite element software to capture stress fields at the tip of cracks and enhance its capability of modelling growth in crack based on this stress field. Stepwise use of this implementation can then be used for damage tolerance evaluation of gas turbine components. To achieve this, some APDL subprograms were developed in order to automate re-meshing of crack region and extraction of stress intensity factors in various 2D and 3D cases. Capabilities of ANSYS to model crack tip stress fields using quadratic and linear elements were validated. Macros to aid in automated re-meshing of crack region and extraction of stress intensity factors from ANSYS postprocessor were developed using ANSYS Parametric APDL for various configurations of crack.
Develop and validate simulation methodology in LS-Dyna for blade impact on containment structures
Fan blade-out simulation studies aim at reducing the overall weight of an aero-engine. In majority of cases, blades are made heavier in order to avoid the remote possibility of fan blade off. Engine case is also overdesigned and hence made heavier to prevent the separated blade from penetrating and impacting other parts such as fuselage, fuel lines etc. The fan blade out event can occur due to foreign object damage (FOD), manufacturing and fabrication defects and fatigue. During fan blade out event, the engine cases must contain the fan blade's kinetic energy through its impact with the containment structure. This structural absorption capacity is called containment.
A Non-Linear Finite Element simulation methodology is developed for the analysis of Gas Turbine Engine Fan Blade-out Containment Structure and based on the developed methodology a parametric analysis of impact on containment structure for various thicknesses of casings and crack is studied. Capability of simulating crack growth using traditional fracture mechanics parameters was found to be lacking in LS-Dyna. Both Sandwich and Hybrid structures were found to be effective in this application. Design with Zylon, instead of Kevlar was found to be superior in terms of absorption of impact energy.
Cooling Concepts Related to Gas Turbine Blades
Gas turbines are used extensively for aircraft propulsion, land-based power generation and industrial applications. They operate at high temperatures of 1200ºC-1500ºC to improve thermal efficiency and power output; however, this temperature exceeds the melting temperature of the turbine blades. Hence, it is imperative that the turbine blades are cooled. The turbine blades are cooled by the air extracted from the compressor. With a combination of cooling techniques, the temperature of the blades can be lowered to approximately 10000C. Rib-Turbulated cooling plays a very important role on this aspect.
The objectives include a literature review on heat transfer characteristics and their correlations for ribbed straight and other passages with and without rotation, CFD analysis of single-pass and twin-pass smooth & ribbed passages, single pass-V ,W, Broken W ribs for static/rotating conditions. The simulations are also to be carried out for different turbulence models.A comprehensive study of available literature has been done and papers with correlations compiled. All simulations for different geometries (straight single ribbed pass, U bend -smooth and ribbed, single pass-V ,W, Broken W ribs) have been carried out as per objectives. The CFD results do show qualitative agreement with experimental data in most cases.
Automotive Torque Converter Design Code
Automotive torque converters even though widely used, they have been developed only by limited commercial enterprises. Torque converter usually located between the engine's flex plate and the transmission which normally takes the place of a mechanical clutch in a vehicle with an automatic transmission, allowing the load to be separated from the power source. It multiply torque when there is a substantial difference between engine and transmission rotational speed, thus providing the equivalent of a reduction gear. The continuous development of transmission for various combat vehicles has led to the need for developing a design procedure for Torque converter for various power ratings.
Torque converter design methodology is finalized and standalone program- SASTCD.exe is developed using available open source software. Coordinates of the pump, turbine, and stator are the output from standalone SASTCD program will be saved in CAD specific format. Torque converter modeling is automated in CAD software using macros, which will automatically generates the pump, turbine, stator blades and torque converter profile for further flow analysis. 1D performance is validated with different CFD simulations. The efficiency of the Torque converter has direct impact on the performance of the vehicle. The performance of the torque converter is improved by better understanding the flow field inside the converter to minimize the flow losses.
Design and Development of Semi-Active Suspension System using MR Dampers
Now a day's the magnetorheological (MR) damper is one of the most promising new devices for heavy machinery and structural vibration reduction. MR Damper meets many applications demands efficiently, because of its large force capacity, robustness, low power requirements, mechanical simplicity and high dynamic range. In recent years MR dampers have received significant attention especially they offer the adaptability of active control devices without requiring the coupled large power sources. MR damper potentially offers highly reliable operation because during power failure mode it can be able to act as passive damper.
MR damper is designed based on parameters like Shear gap and size of the MR valve, MR fluid selection, Magnetic circuit design, Electromagnetic analysis, analytical damping force estimation, material selection and feasible manufacturing techniques. Designed damper has been tested using servo hydraulic machines and damping characteristics have been recorded.
Design & Development of Electronic Parking Brake for an Automotive SUV
Electronic Parking Brake (EPB) is the recent development in automotive brake technology using electronic control. The basic principle of the EPB is - by press of a button on the dashboard, the parking brakes will be actuated using electronically controlled brake actuator unit. This eliminates the use of traditional hand levers and foot pedals that occupy significant space within the vehicle cabin.
Apart from performing the basic vehicle holding function required off of park brakes, the developed EPB systems provides the other functions like automatic release of the Park brakes when driver presses the accelerator, re-clamping using additional force on detection of vehicle motion and the hill-hold function, which applies brakes to prevent roll-back when pulling away on a gradient.
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