The Role of Rubber in Reducing NVH in Automotive Applications

A recent study published in the Journal of Human-Centric Intelligent Systems shows a growing consumer preference for quieter, more sophisticated vehicle sounds. This study brings attention to a shift in automotive sound design strategies to enhance product attractiveness and align with evolving market trends, highlighting the critical importance of noise, vibration and harshness (NVH) reduction.

Rubber components are at the forefront of this engineering challenge and are pivotal in minimizing NVH and enhancing driver comfort. From engine mounts to suspension bushings, these unassuming parts are essential in creating a smooth, quiet ride that consumers demand.

This article explores the critical role of rubber in reducing automotive NVH by examining key components, design considerations and material advancements. 

Understanding NVH in Vehicles

NVH encompasses the full spectrum of unwanted sensory inputs experienced by vehicle occupants. 

• Noise: Energy transmitted via pressure waves through the air, which could include audible disturbances, ranging from wind and road noise to powertrain sounds
• Vibration: Energy transmitted through materials via mechanical oscillation, often felt through the steering wheel, seats or floor
• Harshness: Overall perception of ride quality, including the vehicle’s response to road imperfections and sudden impacts

Reducing NVH enhances passenger comfort, improving customer satisfaction and brand loyalty. More importantly, lower NVH levels contribute to reduced driver fatigue and overall driver safety.

The energy created during vehicle operation has to go somewhere — and without NVH reduction, vibration and heat can wear down parts and potentially cause major components to fail. If they fail at inopportune times, drivers can experience serious injuries. Additionally, broken parts can be significantly costly to fix.

Effective NVH control can help protect drivers and vehicle components by absorbing that energy properly.

Essential Rubber Components for NVH Reduction

Rubber components are instrumental in mitigating NVH issues across various vehicle systems. Their unique viscoelastic properties allow them to absorb and dissipate energy effectively, making them ideal for damping vibrations and isolating noise sources. Some essential rubber components for NVH reduction include:

Bushings

Bushings are cylindrical rubber components that provide a flexible interface between various suspension and chassis parts. They allow for controlled movement while isolating vibrations, reducing road noise and minimizing the transmission of the energy of harsh impacts to the vehicle body. Types of bushings include:

• Control arm bushings: Isolate suspension movement from the chassis
• Sway bar bushings: Reduce noise and vibration from the anti-roll bar
• Subframe bushings: Isolate the entire subframe from the body, reducing overall NVH

Bearings

While traditionally associated with metal components, rubber is essential in modern automotive bearings, particularly in NVH reduction applications. Rubber-to-metal bonded bearings combine the strength of metal with the vibration-damping properties of elastomers. These bearings are commonly used in driveshaft center support bearings to reduce driveline vibrations, strut mounts to isolate suspension movement from the body and steering column bearings to minimize vibrations felt through the wheel.

Isolation Mounts

Isolation mounts are specialized rubber components designed to support major vehicle systems while minimizing the transmission of vibrations. They come in various forms, including:

• Engine mounts: Support the powertrain while isolating engine vibrations from the chassis
• Transmission mounts: Reduce drivetrain vibrations and movement
• Body mounts: Isolate the vehicle body from the frame in body-on-frame constructions
• Hydromounts: Provide adaptive damping as advanced fluid-filled mounts

Advanced isolation mounts like hydromounts may incorporate hydraulic chambers or electronic control systems for adaptive damping across different operating conditions.

Bellows

Bellows are flexible, accordion-like rubber structures that serve dual purposes in NVH reduction. CV joint boots protect constant velocity joints while damping driveline vibrations. Steering rack bellows shield steering components and reduce road noise transmission. In the engine compartment, air intake bellows isolate engine vibrations from the air intake system, reducing noise and improving NVH performance.

Gaskets

While primarily designed for sealing, gaskets also reduce NVH. Valve cover gaskets damp valve train noise, while exhaust system gaskets reduce exhaust leaks and associated noise. Door seals minimize wind noise and vibrations entering the cabin, contributing to interior comfort.

Design Considerations for Rubber Components

Creating effective rubber components for NVH reduction requires carefully considering various factors.

Material Selection

Choosing the right rubber compound is vital for optimal NVH performance. Factors to consider include:

• Hardness (durometer): Softer compounds generally provide better vibration isolation but may compromise durability
• Damping coefficient: Higher damping coefficients offer superior vibration absorption 
• Temperature resistance: Ensure performance across projected operating temperatures 
• Chemical compatibility: Resistance to oils, fuels and other automotive fluids

Recent advances in rubber materials have led to the development of compounds with enhanced damping properties, such as butyl rubber blends and silicone-based elastomers, which offer superior NVH performance in specific applications.

Shape and Geometry

The design shape of rubber components significantly influences their effectiveness in vibration damping. Variable cross-sections allow for different stiffness characteristics in multiple directions. Voids and chambers can be tuned to target specific frequency ranges, while ribbed designs increase surface area for better heat dissipation and damping.

Innovative designs, such as dual-durometer bushings with a softer outer layer and firmer inner core, provide optimal NVH reduction while maintaining the necessary stiffness for vehicle mechanics.

Durability and Environmental Resistance

Ensuring long-lasting performance under various operating conditions is essential. Heat aging resistance helps maintain properties over time, even at high temperatures. Ozone resistance prevents cracking and degradation from environmental exposure, while fatigue resistance allows the components to withstand repeated loading cycles without performance loss.

Considerations for resistance to heat and ultraviolet light, road salt, chemicals, and other environmental factors often involve trade-offs between NVH performance and longevity, requiring careful balance in the design process.

Material Advancements Enhancing NVH Reduction

Ongoing research and development have led to noteworthy advancements in rubber technology for NVH applications, such as:

• New rubber compounds: Advanced rubber materials with superior damping characteristics are making an impact. These materials include magnetorheological elastomers that change stiffness in response to magnetic fields, allowing for adaptive NVH control, and nanocomposite rubbers that incorporate nanoparticles to enhance damping properties and durability.
• Composite materials: Integrating rubber with other materials enhances overall performance. Rubber-metal composites combine the strength of metal with the damping properties of rubber, and fiber-reinforced rubbers improve strength and heat resistance while maintaining flexibility.
• Manufacturing techniques: Innovations in manufacturing processes, such as precision injection molding and the 3D printing of elastomers, improve the quality and consistency of rubber components.

Why Trust Us

At W.N. SHAW & C.O., INC., our expertise in automotive NVH reduction stems from decades of hands-on experience in the mold release industry. This work has given us deep insights into the vital role of rubber components in minimizing noise, vibration and harshness in vehicles. 

We have witnessed the evolution of NVH reduction techniques and materials firsthand, helping develop and test innovative solutions for NVH parts along the way. Our knowledge comes from practical, shop-floor experience and extensive product testing across various automotive applications. This deep understanding of rubber molding processes makes W.N. SHAW a trusted authority by manufacturers of NVH reduction strategies in modern vehicles.

W.N. Shaw Release Agents Power Precision NVH Parts Manufacturing

Rubber is vital for automotive NVH reduction, present in components from bushings and isolation mounts to advanced hydromounts. As vehicle comfort demands increase, manufacturing precision becomes paramount in meeting NVH performance and safety requirements. Partnering with experts is essential for manufacturers looking to stay on the cutting edge of NVH reduction. 

W.N. SHAW has decades of experience in specialized mold release agents for automotive manufacturers. As a globally recognized company based in the United States, our expertise in molding processes and custom formulation capabilities helps manufacturers optimize their production of critical NVH parts. Contact us today to discover how our release agent solutions can enhance your manufacturing of automotive NVH components.