Ageing simulation of a hydraulic engine mount: A data-informed finite element approach

Abstract

Hydraulic engine mounts are key elements in an automotive vehicle suspension system that typically experience a change of their designed function during their working lifetime due to progressive material ageing, primarily from the elastomeric component. Ageing of the engine mount, resulting from severe and continuous mechanical and thermal loads, can have a detrimental impact on the ride and comfort and long-term customer satisfaction. This paper introduces a new practical methodology for simulating the ageing behaviour of engine mounts resulting from the change in properties of their elastomeric main spring component. To achieve this, a set of dynamic mechanical thermal analysis tests were conducted on elastomeric coupons taken from a set of engine mounts with different service and ageing conditions. These experimental results were used to characterise the change in mechanical response of the elastomer and to build up an empirical elastomer ageing model. Then a finite element model of the main spring was developed that used the elastomer ageing model so that the ageing behaviour of the engine mount could be simulated. The resulting ageing model was verified by using experimental results from a second batch of ex-service engine mounts. The results show an increasing trend of the vertical static stiffness of the engine mounts with distance travelled (or age) up to a certain distance (approximately 95,000 km). The trend is then reversed and a softening effect is observed. Moreover, the results reveal that both the maximum stiffness value and the distance travelled at the peak stiffness decrease as the temperature increases.

Novel fluid inerter based tuned mass dampers for optimised structural control of base-isolated buildings

“…Specifically, the design of these mounts was based on the lever arm model of the Dynamic Anti-resonant Vibration Isolator (DAVI) concept, first patented in 1967 by Flannelly [31], which is also an inerter. More recent studies of the application of these mounts can be found in [32]- [34]. Devices that exploit relative acceleration to produce inertial force for civil engineering applications were also being developed as modifications to viscous dampers in the late 1990ssee the tuned viscous mass damper (TVMD) described in [35] and references therein.…”

Tensile Properties Degradation of Thermally Aged NR/EPDM Blend and Nanocomposites for Engine Mounting

“…It is sensitive to temperature [1] hence the life span and performance of an engine mount affected by different temperatures acting on it. However, the change in mounting criteria is highly contributed by the elastomeric component inside the mount [2]. Therefore, understanding the effect of materials structure on the thermal ageing behavior is crucial for engineers and designers to improve the system.…”

“…There are numerous number of studies carried out to improve the properties of engine mounting to isolate the engine vibration, optimizing the engine performance, extending the engine's life span and saving power consumption [2,[5][6]. Our previous studies on GNPs reinforced NR/EPDM blends proven to increase the heat dissipation [4] and improve vibration damping [7]; reflecting their potential to be used in the engine mounting.…”

Design and testing of a frictionless mechanical inerter device using living-hinges

“…Beyond its direct application, the DAVI concept was also used to schematically represent the inertial effect of the first fluid inerter design. This fluid inerter was incorporated into automotive engine mounts [7], where the DAVI lever arm model was used to approximate the effect of a rotating annulus of fluid (called the inertia track) inside the mount -see also [8][9][10]. In addition to this, applications of inerter-like devices in civil engineering evolved from modifications to viscous dampers, that date back to the late 1990s, and eventually resulted in tuned-viscous-mass-dampers -see the discussion in [11] and references therein.…”