Bulk wave propagation analysis of imperfect FG bio-composite beams resting on variable elastic medium

Bio-composites are outstanding alternatives to prevalent biomaterials in medical instruments due to their supreme material properties. On the other hand, mechanical analyses of bio-systems should be carried out to optimize the designed biomedical applications such as medical implants. Therefore, bulk wave propagation analysis of functionally graded (FG) bio-composite beams could serve as design targets of biomedical structures. Some applications like medical implants have a layered structure and FG composites will be an appropriate choice for constitutive material of such structures. In the current study, the influence of imperfection on the propagation of bulk waves in FG bio-composite beams with biomedical applications lying on a variable elastic medium has been evaluated for the first time. The constitutive materials of FG bio-composite beams are hydroxyapatite and gold alloy which are common materials in the biomedical industry. To determine the effective material properties of the structure under study, the conventional porosity-dependent homogenization scheme has been implemented. Various distribution patterns have been accounted for variable elastic medium. Moreover, a refined higher-order shear deformation theory and Hamilton ' s principle have been exerted to obtain the partial differential governing equations and the derived equations are analytically solved via a harmonic function. To check the accuracy of the used methodology, the obtained result has been validated firstly with former investigations. Eventually, the sensitivity of various considerable parameters has comprehensively been probed and discussed. It is found that some parameters including wave number, power law index, and elastic foundation have positive effects and some parameters including slenderness ratio, xi parameter, and imperfection coefficient have negative effects on the propagated bulk waves. Also, the sinusoidal pattern possesses less increasing effect than other ones.