Spray deposited metal-carbon fiber reinforced polymer hybrid structures
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ay Deposited Metal-Carbon Fiber Reinforced Polymer Hybrid Structures P.S. MOHANTY and A. ARGENTO Tubular construction forms the basis of many common structural and manufacturing systems such as driveshafts, cross-car beams, framework, mounting brackets, and boring bars. Weight reduction without degradation of stiffness, damping, and frequency characteristics is typically a goal of the design of all these components and can be achieved by hybrid structures consisting of metals combined with fiber-reinforced polymeric (FRP) composites. The concept of combining metal and carbon composites to achieve optimum mechanical properties and low weight has been investigated in References 1 through 3. It has been shown that extremely high stiffness can be obtained through the hybrid combination of a steel tube core and carbon fiber/epoxy casing. There are, however, some disadvantages to having the FRP outside the metallic core. Namely, the FRP tends to not wear well, lacks damage resistance, absorbs moisture, and cannot be welded. Therefore, these designs resulting from pultruding, wrapping, or filament winding carbon over metal can be improved by adopting the arrangement shown in Figure 1, i.e., having the metal outside the polymer core. Manufacturing such structures, however, is problematic especially if extremely high bond strength at the FRP/metal interface is required or if a thick metal casing is needed. In this work, prototype tubular structures are described consisting of an FRP core and spray-deposited steel casing. The article reports the design and manufacturing of the structures and presents the results of microstructural analysis and mechanical tests on the structures. The potential of the hybrid FRP/steel arrangement is examined using an anisotropic rotating Timoshenko beam model[1,2,3] incorporating gyroscopic effects and layerwise variation in mechanical properties. The model also includes internal and external viscous damping. Thus, the model permits structures having construction like that in Figure 1 to be designed based on predictions of natural frequency,
P.S. MOHANTY, Assistant Professor, and A. ARGENTO, Associate Professor, are with the Department of Mechanical Engineering, University of Michigan–Dearborn, Dearborn, MI 48128-1491. Contact e-mail: [email protected] Manuscript submitted March 19, 2002. METALLURGICAL AND MATERIALS TRANSACTIONS A
stiffness, transient response to loads, and failure. In the foregoing, interest is in the structure’s bending frequencies and bending stiffness; these are determined from the model in the following way. The model consists of a set of partial differential equations for the structure’s displacements and rotations as functions of the axial coordinate and time. A system of ordinary differential equations results upon satisfaction of spatial dependence for clamped-free support conditions using Galerkin’s method. A numerical eigenvalue problem defined by the homogeneous version of this system gives the structure’s free vibration natural frequencies. Static bending stiffne
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