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Technical Paper

Acoustic Tuning of Lightweight Vehicle Interior Systems

2001-04-30
2001-01-1628
This paper discusses the approach and application of controlling material and manufacturing parameters in development of lightweight acoustic interior systems. First addressed is the theoretical premise of noise control mechanisms and their relationship to material property/process sensitivity through poroelastic model simulation. The optimal balance of sound transmission loss and absorption in achieving optimally tuned acoustic performance is then presented along with material sample and in-vehicle experimental results. The ability to acoustically tune the vehicle interior to a desired sound level and frequency content through proper design & control of the elastic porous properties achieved by unique acoustic material/process flexibility & capability is demonstrated.
Technical Paper

Effects of Brake Pad Boundary Contact Surfaces on Brake Squeal

2011-09-18
2011-01-2355
The disc brake corner assembly is comprised of several subsystems (brake pad, caliper, rotor etc.) which have interfaces between two or more of these structures. The brake pad assembly as the subsystem connecting the rotor to the caliper has specific areas of contact which influence the onset and potential to control brake squeal. The primary excitation interface occurs between the friction pad and rotor surface. The contact is initiated by the piston apply force on the brake pad insulator. Contact interface reaction forces, displacements and deformations are generated and form the natural and geometric boundary conditions of the overall system. Brake squeal characteristics are strongly affected by these conditions. The study focuses on brake system dynamic response to interface contact conditions. The brake insulator and pad assembly interacting with the brake piston as well as caliper are evaluated.
Technical Paper

Brake Insulator Development: Thermal and Structural Dynamic Semi-Empirical Design Guidance/Data Synthesis Methods

2006-10-08
2006-01-3219
The brake insulator performs a significant function when properly designed in controlling the brake system high frequency dynamic instabilities leading to brake squeal. The second major challenge is thermal management. It provides the direct heat flow, storage and corresponding temperature differential profile between the rotor and piston. Suboptimal thermal control can lead to lower operational bands of damping outside of the peak loss factor range, variation in modal dynamics with temperature, heat aging and degradation of elastomer/visco-elastic polymer physical properties [2, 3]. Design of the insulator is dictated by the unique squeal signature (and associated thermal cycles) specific to the brake corner architecture. Short time frame insulator solutions are typically required in the later development stages with no latitude for design modification flexibility.
Technical Paper

Development of Cold Noise Brake Insulator Solutions

2009-10-11
2009-01-3035
The environmental effect on brake system noise characteristics has introduced increased expectations in overall performance as well as associated challenges in the design of brake insulators that can provide optimal noise control within specific temperature extremes. The condition of cold noise brake squeal which is classically defined between 0 to 50C (pad lining temperature) and environmental conditions as low as -50C depending on regional applications has become a major part of customer requirements. This is evident by the proliferation of vehicle and dynamometer test validation protocols (e.g. Minneapolis City Traffic (MCT), GMW 14591, Ford Cold Noise Procedure (CTEP 420), J2521, Federal Mogul (FM204B)) which devote a significant part of the cumulative brake squeal occurrences within the cold noise regime.
Technical Paper

Effect of Brake Insulator Bond State on Damping Performance

2010-10-10
2010-01-1700
Meeting specific bonded insulator attachment specifications depend on the type of bonding polymer selected as well as application conditions. These conditions include initial apply parameters (time, temperature and pressure), backing plate surface characteristics (surface material, flatness, finish) and strength properties that avoid cohesive, adhesive or mixed mode failures during operating life of the braking pad assembly. “T-pull” and “Lap Sheaf testing provide an overall quantitative method to determine tensile and shear load/deflection properties. They do not assess the three dimensional dynamic stress state of the bond during braking conditions which involve the influence of temperature, apply pressure, rotational inertial forces and cyclic frequency/strain rate effect. The operational factors which change the state of bond have an effect on damping performance and ability to control overall system noise.
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