Simulation of a Composite Piezoelectric and Glass Fiber Reinforced Polymer Beam for Adaptive Stiffness Applications

Glass Fiber Reinforced Polymer (GFRP) beams have shown over a 20% decrease in weight compared to more traditional materials without affecting system performance or fatigue life. These beams are being studied for use in automobile leaf-spring suspension systems to reduce the overall weight of the car therefore increasing fuel efficiency. These systems are subject to large amplitude mechanical vibrations at relatively constant frequencies, making them an ideal location for potential energy scavenging applications. This study analyses the effect on performance of GFRP beams by substituting various composite layers with piezoelectric fiber layers and the results on deflection and stiffness. Maximum deflection and stress in the beam is calculated for varying the piezoelectric fiber layer within the beam. Initial simulations of a simply supported multimorph beam were run in ABAQUS/CAE. The beam was designed with symmetric piezoelectric layers sandwiching a layer of S2-glass fiber reinforced polymer and modeled after traditional mono leaf-spring suspension designs with total dimensions 1480 × 72 × 37 mm³, with 27 mm camber. Both piezoelectric and GFRP layers had the same dimensions and initially were assumed to have non-directional bulk behavior. The loading of the beam was chosen to resemble loading of a leaf spring, corresponding to the stresses required to cycle the leaf at a stress ratio between R = 0.2 and 0.4, common values in heavy-duty suspension fatigue analysis. The maximum stresses accounted for are based on the monotonic load required to set the bottom leaf surface under tension. These results were then used in a fiber orientation optimization algorithm in Matlab. Analysis was conducted on a general stacking sequence [0°/45°]_s, and stress distributions for cross ply [0°/90°]_s, and angle ply [+45°/−45°]_s were examined. Fiber orientation was optimized for both the glass fiber reinforced polymer layer to maximize stiffness, and the piezoelectric fiber layers to simultaneously minimize the effect on stiffness while minimizing deflection. Likewise, these fibers could be activated through the application of electric field to increase or decrease the stiffness of the beam. The optimal fiber orientation was then imported back into the ABAQUS/CAE model for a refined simulation taking into account the effects of fiber orientation on each layer.