Short-Term Flexural Creep Behavior and Model Analysis of a Glass-Fiber-Reinforced Thermoplastic Composite Leaf Spring

Present work investigated the short-term flexural creep performance of fiber reinforced thermoplastic injection molded leaf springs. Unreinforced polypropylene, 20 wt % short and 20 wt % long glass fiber reinforced polypropylene materials were injection-molded into constant thickness varying width mono leaf spring. Shortterm flexural creep tests were performed on molded leaf springs at various stress levels with the aid of in-house developed fixture integrated with the servo-hydraulic fatigue machine. Spring rate reduction is reported as an index for the accumulated damage. Experimental creep performance of molded leaf springs for 2 h was utilized to predict the creep performance with the aid of four parameter HRZ model and compared with 24-h experimental creep data. Test results revealed that HRZ model is sufficient enough to predict short-time flexural creep performance of engineering products over wide range of stress. Test results also confirmed the suitability of long fiber reinforced thermoplastic material for creep application over other considered materials. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 3679-3686, 2011