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Dynamic stability of a flexible cam±follower system is considered. The shaft±cam±follower assembly is modelled by a single degree-of-freedom system. In the analysis, transverse and rotational flexibility of the camshaft along with flexibility and damping of the follower are taken into consideration. The governing equation of motion for the follower is given by a linear, second-order, ordinary differential equation with time dependent coefficients. In general, this class of equation is known as a second-order Hill's equation. The time responses of the cam±follower system for an eccentric circular cam for different rotational speeds are determined. In addition, stability analysis based on Hill's infinite determinant is performed, and the effects of operational speed and damping on the stability are determined. For the special case of the cam±follower system that has been considered, it has been found that the system is stable for low values of the angular speed of the cam. As the speed is increased gradually, a few unstable regions occur. In general, damping shows a significant effect on stabilizing the cam±follower system.

Dynamic response of single lap joints, subjected to a harmonic peeling load is studied theoretically and experimentally. In the theoretical part, dynamic response of a single lap joint clamped at one end and subjected to a harmonic peeling load at the other end is investigated. Adherents are modeled as Euler-Bernouli beams joined in the lap area by a viscoelastic adhesive layer. Both axial and transverse deformations of adherents are considered in deriving the equations of motion. The effects of adhesive layer thickness, mechanical properties and its loss factor on the dynamic response of the joint are investigated. Furthermore, effects of defects such as a void in the lap area on the dynamic response of the joints are studied. The results showed that frequencies where peak amplitudes occurred were little dependent on the adhesive loss factor. However, peak amplitudes reduced for joints with a higher adhesive loss factor. Furthermore, the results indicated that for the joint geometries and properties investigated the system resonant frequencies were not affected by the presence of a central void covering up to 80% of the overlap length. In the experimental part, single lap joints were fabricated using 6061-T6 Aluminum. Adherents were joined together using Hysol EA 9689 adhesive film. Joints with various central voids were manufactured by removing adhesive film from the desired area of lap joints prior to bonding adherents. Dynamic responses of the joints were investigated using the hammer test technique. The system response was measured using both an accelerometer and a noncontact laser vibrometer. The natural frequencies of the joints obtained by using the laser vibrometer were very close to those obtained theoretically. However, natural frequencies obtained by using an accelerometer depended on the accelerometer location in the system, which was attributed to its mass contribution to the over- all system mass. A central void covering less than 80% of the overlap length had little effect on the system resonance frequencies. This was in agreement with the theoretical results. In contrast total system-damping ratios were a function of the void size. Joints without a void exhibited higher damping.

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