Pushing the NVH performance envelope of rubber components at Tokai Rubber Industries

Engineering the NVH performance of a vehicle is one of the most demanding challenges in automotive design, especially when it comes to deciding which materials to use, how to shape components and where to position them. The NVH expertise gained during decades of developing innovative and effective anti-vibration rubber products helped Tokai Rubber Industries (TRI) to successfully take up this new supplier role. Continuous investments in rubber material research and the deployment of a simulation-driven product development enable TRI to regularly introduce new design concepts. LMS simulation and testing solutions assist TRI in shaping new products that further improve NVH performance and reduce production cost.

Tokai Rubber Industries (TRI) is currently the largest supplier of vibration-suppressing rubber products in Japan. Over the last 70 years, it gained the trust of many customers across different industries by designing and producing top-class rubber and resin based parts. TRI delivers anti-vibration rubber products, hoses, noise insulators and interior parts to automotive manufacturers around the world. Its activities in other markets include the development of anti-vibration rubber devices for several transportation systems, for civil construction and the most diverse industrial purposes. TRI is also active in consumer and business electronics, as it supplies anti-vibration products for automotive CD players, and precision components and flexible circuit boards for office printers, for example.

The diverse material characteristics of rubber and its numerous combinations with metal, glass, plastic, resin, foam or composite material offer infinite possibilities to reduce vibrations and to tackle structure-borne noise issues. To take full advantage of these opportunities, TRI continuously invests in rubber material research to increase its capability to develop innovative rubber types that combine superior NVH characteristics with reduced production costs. As an example, TRI develops liquid-filled Active Control Mount (ACM) devices, which directly eliminate firing order vibrations before they can be transmitted to the structure of the vehicle.

The introduction of LMS Test.Lab increased testing efficiency significantly, as it operates according to an integrated process-oriented flow that efficiently captures all sequential testing operations.






To succeed in implementing shorter development lead times with reduced development resources and expenses, automotive OEMs no longer opt for suppliers that solely develop top-class products and offer outstanding technical expertise. As tier-one system suppliers are expected to take on increased levels of responsibility, they require the capability to efficiently develop new products, integrate them into a new vehicle prototype, and fine-tune the overall vehicle NVH performance. TRI partners and collaborates with OEMs and other suppliers by implementing design, simulation, analysis and testing capabilities that previously were the exclusive domain of the OEMs. Adopting these capabilities helps anticipate how new products will operate on their own and integrated into larger assemblies. More in particular, the use of predictive software solutions early in the development offers TRI engineers a better understanding of how structural aspects impact different noise and vibration performance attributes. This enables them to select the most appropriate design concepts up-front and efficiently move the development of new product designs into innovative directions. Later in the development, more detailed analytical assessments in combination with systematic test-based validations make it possible to gradually optimize specific characteristics and establish the most favorable tradeoffs between conflicting attributes.

For over 20 years, TRI builds on LMS testing solutions to perform its extensive range of NVH-related testing assignments. During this longstanding relationship, TRI successfully deployed LMS SCADAS front-end hardware, LMS CADA-X, and more recently,
LMS Test.Lab test software. The extensive NVH engineering know-how accumulated while using these systems provides TRI a head start for each new product development program that is initiated. In addition, the recent introduction of LMS Test.Lab increased testing efficiency significantly, as it operates according to an integrated process-oriented flow that efficiently captures all sequential acquisition, analysis and post-processing steps.

Tests that TRI engineers perform on complete vehicles typically occur in a hemi-anechoic chamber, which is equipped with a chassis dynamometer and a vehicle shaker. Under specific driving conditions, the sound and vibration responses at multiple interior locations and across a wide range of system components are acquired. Afterwards, engineers perform TPA and ASQ analyses to identify the contribution of individual devices to both structure-borne and air-borne noise, and to evaluate this information in context of the overall NVH performance of the vehicle. Important in such tests are LMS Test.Lab’s on-line processing features, which allow TRI engineers to draw intermediate conclusions on the basis of partially acquired data. The insights gained from these early analyses enable them to adapt the focus of the remaining testing work, while still having the test object at their disposal. Specific assessments TRI engineers perform on individual components serve a different purpose. They install components on test benches to verify the strength and durability performance characteristics that have been predicted earlier on. These test results are then used in a feedback loop in order to further optimize the design and to obtain a more favorable cost-function equation.

Since 1990, TRI started with the introduction of CAE solutions in its product development workflow. Today, TRI engineers use LMS SYSNOISE to simulate emanated noise levels at interior and exterior vehicle locations, and LMS TWR to monitor mechanical endurance. The strategy of TRI is to perform full-vehicle NVH simulation whenever feasible, and use the outcome to support decisions related to design optimizations and troubleshooting actions. In parallel to vehicle-level evaluations, component and system simulations are performed to predict resonance frequencies and to detect structural areas facing extreme strength and durability.

As a supplier of engine mount systems, TRI is often involved in idle vibration optimization. To drill down on these disturbing vibrations, TRI engineers run modal tests and simulations to investigate complex decoupled resonance phenomena, including rigid engine modes, bending and twisting body modes and steering system resonances. Equally important in these assessments are the analysis of transfer paths and the quantification of individual engine mount contributions. In the case of a small four-wheel-drive vehicle, engineers used LMS RMA and TPA software to evaluate the vehicle model for specific frequencies and retrieve the transfer paths that matter most. After this, they validated the prediction accuracy of the vehicle model through comparison with test results. Based on these analyses, the engineers proposed two countermeasures to reduce the idle vibrations that occurred around 600 rpm engine speed. The first option was to decrease the fore and aft dynamic spring characteristics of both engine mounts, but the engineers did not select this solution because it increased vibration levels during vehicle acceleration and deceleration. Instead, they selected the second option, which included the installation of a liquid-filled engine mount at the right-side mount position and the adaptation of its phase characteristics in the vertical direction.

Top product performance and local technology expertise

To efficiently support its intensive technological relationships with Asian customers, TRI opened a dedicated technical center in Komaki, Japan. More recently, TRI established a second center in Novi, Michigan, which it uses to serve North American and European automotive markets. This technical center is equipped with a 4-wheel chassis dynamometer in a hemi-anechoic chamber and a 4-poster vehicle shaker along with component testers for durability testing in single and multiple axes. TRI engineers use this center’s test infrastructure and software seats to productively execute and coordinate in-depth technical development and integration work. The local presence enables them to maintain regular face-to-face customer contacts without language barriers, and makes it easier to more frequently run full-system test cycles on customers’ prototype vehicles and modules.

TRI invests a lot in establishing and maintaining successful customer relationships by developing effective and affordable anti-vibration rubber products and offering multiphysics expertise that is provided locally. The capability to leverage tools, technology and expertise is essential to TRI in order to systematically realize technical advancements that consequently push the NVH performance envelope of its innovative product portfolio.