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Ocean waves are one of the cleanest and most abundant energy sources on earth, and wave energy has the potential for future power generation. Triboelectric nanogenerator (TENG) technology has recently been proposed as a promising technology to harvest wave energy. In this paper, a theoretical study is performed on a duck-shaped TENG wave harvester recently introduced in our work. To enhance the design of the duck-shaped TENG wave harvester, the mechanical and electrical characteristics of the harvester's overall structure, as well as its inner configuration, are analyzed, respectively, under different wave conditions, to optimize parameters such as duck radius and mass. Furthermore, a comprehensive hybrid 3D model is introduced to quantify the performance of the TENG wave harvester. Finally, the influence of different TENG parameters is validated by comparing the performance of several existing TENG wave harvesters. This study can be applied as a guideline for enhancing the performance of TENG wave energy harvesters.

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Due to their complexity, detecting and analysing damage modes in composite honeycomb sandwich panels can be difficult. This article describes the way in which a three-point bending test (3PBT) was performed on a glass fibre aluminium honeycomb sandwich panel (HSP). Acoustic emission (AE) was used to identify damage signals, which were then analysed to determine the positions and characteristics of defects. To locate damage positions, Delta-T mapping was used. The test load was progressively applied in three phases, with the specimen being inspected visually during each phase. A scanning electron microscope (SEM) showed that the most significant damage was local crushing under the test load, which caused matrix cracking, fibre breakage and pull-out. Damage progression and the damage mode were detected using the cumulative energy and frequency spectra of the AE sources for each phase. Matrix cracking frequencies ranged from 30 kHz to 100 kHz, while fibre damage modes ranged from 157 kHz to 322 kHz. The findings highlighted the utility of Delta-T mapping in locating damage positions on sandwich structures under testing. The investigation also emphasised the value of studying frequency spectra and cumulative energy when analysing AE signals.

The paper proposes the use of a cam with a reciprocating or oscillating follower for the elimination of the fluctuation of the torque input to a planer mechanism. The cam is fixed to the input shaft, which is rotating at a uniform speed, and • the follower is maintained in contact with the cam by means of a spring. The expression of the input torque, which is required to drive a planar mechanism at a constant input speed, with the output leads and inertia forces considered, is derived. The cam profile is designed such that the cam input torque counters the fluctuating part of the mechanism input torque. This condition is employed in deriving the cam design equation, which is a differential equation describing the follower dsplacement. A special numerical method is proposed for the solution of this equation. Also, a formula is derived for the contact force between the cam and follower. This formula is applied at different mechanism positions, after the solution of the cam design equation, to check the contact between the cam and follower. The proposed method is applied to a four-bar linkage by using a disc cam with an oscilating follower as a numerical example.