Failure Simulation and CAE Testing Loop Strategy for Load Case Derivation for Cable Mounting Clamp

Control Cables are used in automobiles to transfer loads and motions as intended and required by the driver. These cables are supported at multiple points by clamps, which are mounted at suitable locations. The Clutch-cable is one of the cables routed through clamps mounted on the engine and the vehicle-chassis. During the vehicle’s travel on the rough road, the powertrain, supported by flexible mounts, tends to swivel, generating relative motion with respect to the chassis. As one end of the clutch-cable is mounted on the chassis and other on the vibrating engine, this relative movement contributes to the additional forces on the clamps. These forces, sometimes, lead to the clamp’s failure. Thus, the knowledge of load behavior is important for failure investigation and further optimization of the clamp design. The failure of the engine-mounted clutch-cable-clamp was observed in the vehicle testing on the rough road. The investigation attributed this failure to cable movement caused by the multiaxial rotating motion of the engine assembly with respect to the vehicle chassis. As the magnitude and direction of the forces were unknown, initial static-structural CAE was performed to locate the maximum stress zone same as that of the failed part. Then these locations were used for measuring the stress values with strain gauges in vehicle testing. Using these stress values and directions, CAE load case was further optimized and used for validation of the countermeasure design. The comparative fatigue life calculations using the derived CAE methodology showed enhancement in the fatigue life of the countermeasure design. The improved design of the bracket was successfully validated through physical testing. This paper presents the experience of failure simulation and methodology followed to devise a CAE validation method for clutch-cable-clamp, which is under the load due to relative movement of the mounting bases.