Design and production of a piezoelectric energy harvesting system integrated to aluminum honeycomb sandwich panels

Smart materials are defined as materials that can change their properties in response to external stimuli. Several types of smart materials are in use today, such as shape memory alloys, photoactive and piezoelectric materials. Applying mechanical stress to a piezoelectric material causes an electrical difference in the polarization direction of the material. This behavior can be used to generate electrical energy. Today, piezoelectric materials are widely used for electrical power generation in small electromechanical systems, such as MEMS or sensor nodes in aircraft. Composite sandwich technology is also used extensively, for example in wings and ailerons, because it is incredibly light yet structurally rigid. These structures mainly combine the advantages of two or more layers of different elements and enhance their properties. An aluminum honeycomb sandwich is a type of composite sandwich consisting of aluminum walls and a honeycomb core. Aluminum honeycombs have applications ranging from aerospace to marine. Various studies have explored mechanical energy harvesting using piezoelectric patches placed directly on composite panels. However, surface placement of piezoelectric materials can lead to reliability issues due to their exposure to ambient conditions. Consequently, there is a gap in the current literature regarding the embedding of piezoelectric materials within the composite for energy harvesting. The objective of this study is to embed a piezoelectric energy harvesting system into an aluminum honeycomb sandwich panel geometry and to evaluate the performance and dynamic parameters of the combined system. For this purpose, finite elements and experimental methods are used to design the unified structure and to test the final structure. A parametric code is developed for both the piezoelectric energy harvesters and the aluminum honeycomb sandwich panels, and then the physical system is fabricated. Finally, modal tests are performed on the structure and a custom-build experimental setup is utilized to assess the energy harvesting performance of the proposed system.