In a contemporary world, expeditious development in mobility and automobile sector leads to the stringent evaluation, customer ride quality and comfort. Moving towards the high torque and high-performance vehicle adequately designed with consideration of complex behavior of dynamic vehicle in which significant role are played by the chassis, suspension modules and brake components, allowing the vehicle confidentially to maneuver around at all crucial conditions. Although these components can endeavor high energy load and distributions, but high loads and elastic deflection can significantly alter vehicle performance. One such phenomenon, disc brake component of high torque vehicle is increase in pedal travel which arise of higher 3-dimensional excitation. In a traditional Uniaxial vibration shaker, uniaxially excites the components in all three directions independently. Assuming that excitation on all three directions is independent to each other, practically the components vibrate along Three direction. An event that never occurs in single axis excitation can be detected by the simultaneous multi-axis excitation. In order to fulfil the requirement of applying the load as close as possible to the actual environmental load condition, the method of sequentially applying uniaxial excitation in all three directions has been introduced, a multi axis vibration. Due to stringent validation and testing road condition in which vehicle experience severe vibration in all three-axis simultaneously is consider to stimulate in rig level evaluation which leads to foundation for multi-axis fixture development. Design of multi-axis fixture based on variable consideration and vehicle dynamics, calculation of load and distribution on the brake components for one-on-one stimulation in rig. For spongy pedal travel (pedal sinking) analysis with correlation between rig to road stimulation twin pot caliper had taken for validation which can stimulate higher braking torque. Resonance frequency of twin-pot caliper captured in single-axis and multi-axis vibration fixture for a frequency range of 5-300 Hz for 1 g vibration input, comparison of multi-axis fixture to single-axis fixture about 25.2% shift of modal frequency. Independently excitation of single-axis fixture in all three directions, which increases in pedal travel observed only on lateral direction excitation whereas multi-axis fixture failure observed in vertical direction same as a vehicle condition. Fluid consumption of Twin-pot caliper is 16 cc (actual consumption about 4.5 cc) in vertical direction on multi-axis vibration fixture compared to single-axis fixture is about 5.10cc. Vehicle dynamic and lateral force mechanism acting on each corner module and disc brake component are varies rapidly so design of multi-axis vibration fixture varies form model to model, factors which plays a major role on fixture development is CG point of brake component, disc brake installation angle, banking angle, mounting direction, weight of brake component. This paper presents examination of increase in pedal travel of disc brake segment due to dynamic vibration and lateral loads in proto-development stage by introduction of testing fixture coherence to that of vehicle. For actual stimulation of vehicle condition experimentally, multi-axis vibrational fixture was developed compared to traditional testing method i.e., uniaxial vibration fixture. Method of fixture development for three axis excitation of brake component in vibration shaker & correlated with various conditional test tracks. Disc brake component which subjected to uniaxial vibration on vertical direction in which increase in pedal travel were observed on multi-axis vibration fixture compared to uniaxial fixture (based on brake fluid consumption results). In brake caliper resonance test for 1g vibration & 5-300 Hz frequency, multi-axis fixture position aggravates the component more compared to the various other components mounting position. The occurrence of mode shapes & higher acceleration level observed on multi-axis fixture position compared to various mounting position on vibration shakers. By using Multi-axis vibration can meet the practical relevance, minimization test time & multipoint excitation can be applied to brake component and simulate failure as per vehicle conditions.
Mr. Anand Ramamoorthy, General Manager -NVH, Brakes India Private Limited; Mr. Hariharasudhan Kumar, Engineer-NVH, Brakes India Private Limited; Mr. Venkatesh Kitchanna, Deputy Manager- NVH, Brakes India Private Limited; Mr. Koventhan Selvam, Engineer-NVH, Brakes India Private Limited