Integration of piezoelectric stacks in components using powder bed fusion

Abstract

Laser-based powder bed fusion of metals (PBF-LB/M) is the most commonly used additive manufacturing process for fabricating complex metal parts by selective, layer-wise melting of metallic powder using a laser beam. This manufacturing technique can easily fabricate parts with complex geometries that cannot be fabricated using conventional manufacturing processes. These parts with complex geometries are generally used by aerospace and space industries, and advancement in functionalization of additive manufactured parts is highly beneficial to these industries. However, the parts constructed using additive manufacturing are monolithic, stiff, and lightweight and hence, they are vulnerable to high amplitude resonant vibrations. This is due to the low damping factor of the materials used and the absence of interfaces and connections that contribute to structural damping in conventional structures. The integration of piezoelectric materials within these structures would enable the control of vibration characteristics. The techniques presented in this study will enable a high level of freedom in the placement of piezoelectric materials and investigate the potential of merging parts constructed using additive manufacturing with piezoelectric materials. Furthermore, a technique to track the stress state during the integration process, which is crucial for the pre-stress evaluation of integrated piezoelectric stacks, is presented and shows characteristics similar to a force cell. Pre-stress is successfully tracked during integration and in some concepts tensile stress onto the piezoelectric material is occurring. Finally, to verify the functionality for potential piezoelectric damping, power conversion was reported with laser vibrometer measurements and FE validation.

Implementation of tunable frequency-dependent stiffness elements via integrated shunted piezoelectric stacks

“…(c) Stiffness change (real part) around the electrical resonance ωe of a resonantly (Z = L) shunted transducer, adapted from [8,16]. the reduction of resonant vibrations has also been reported in literature [17][18][19][20], mainly because they offer a high electromechanical coupling coefficient of the transducer in the struts constituting truss structures.…”

“…The concepts introduced in the previous section are brought to reality using a sample that was produced by rapid prototyping [20]. The truss is created using selective laser melting of aluminium powder.…”

“…In this work, we move one step forward towards structures with adaptive dynamics, and numerically and experimentally demonstrate frequency dependent connectivity switching using a piezoelectric stack in a braced metallic frame, also in a non-resonant regime. The 3Dprinted aluminium frame with integrated piezo stack, shown in figure 3, was originally reported in [20]. The out of resonance stiffness modification of a unit cell of an additively manufactured lattice material can be seen as a step towards the implementation of adaptive metamaterials postulated in [23].…”