Mechanical Behavior and Fatigue Studies of Rubber Components Used in Tracked Vehicles

In this study, a styrene butadiene rubber, which is similar to the rubber used in road wheel backer pads of tracked vehicles, was investigated experimentally under monotonic and fatigue loading conditions. The monotonic loading response of the material was obtained under different stress states (compression and tension), strain rates (0.001/s to 3000/s), and temperatures (-5C to 50C). The experimental data showed that the material exhibited stress state, strain rate and temperature dependence. Fatigue loading behavior of the rubber was determined using a strain-life approach for R=0.5 loading conditions with varying strain amplitudes (25 to 43.75 percent) at a frequency of 2 Hz. Microstructural analysis of specimen fracture surfaces was performed using scanning electron microscopy and energy dispersive x-ray spectroscopy to determine the failure mechanisms of the material. The primary failure mechanisms for both loading conditions were found to be the debonding of particles on the order of 50 to 200 μm. INTRODUCTION Rubber components in military vehicles must overcome extreme loading conditions due to the harsh service environment such as high temperature, high friction and complex loading [1]. Due to the harshness of environment, rubber components often fail prematurely, causing a vehicle to become unusable in the field. Efforts have been aimed at studying the factors affecting the bushings, backer pads, road wheels and suspension of tracked military vehicles [1]. The components of focus in this study, road wheel backer pads, are failing in the field at mileages that are approximately one-half of the design target. Understanding the loss in strength under such harsh conditions is of prime importance in increasing the component life. Thus, the micromechanisms of deformation and failure of the material must first be established under different loading conditions so that material and fatigue models may be developed and implemented. Figure 1: Methodology for using the history dependents ISV model implemented into a finite element code while using the MSF as a post-processor. Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.