Chapter 30 Identification of Nonlinear Characteristics of an Additive Manufactured Vibration Absorber Cristiano Martinelli, Rohit Avadhani, and Andrea Cammarano Abstrac t Additive manufacturing has become increasingly popular in the last decades and has shown great potential for designing and manufacturing innovative design solutions. Recently it has been demonstrated that additive manufacturing can be used to create monolithic compliant mechanisms that can avoid assembly and relative movement between components, showing considerable advantages in their use in harsh environments (i.e. space applications). In this paper, we explore the possibility of adopting 3D-printed compliant mechanisms as tuned-mass vibration absorbers: the challenge is to identify the characteristics of an equivalent nonlinear oscillator that can be used to assess the performance of the absorber. The experimental and numerical results show that the proposed compliant mechanism offers a complex nonlinear dynamic behaviour and it can effectively act as a vibration absorber for a simple cantilever beam. Keyword s Nonlinear parameter identification · Nonlinear dynamics · Additive manufacturing · Compliant mechanisms · Tuned vibration absorber 30.1 Introduction Compliant mechanisms are monolithic flexible structures that achieve the desired motion thanks to their deformation [1– 3]. Such flexible structures can effectively bypass the main disadvantages of classical rigid mechanisms [4–7], i.e. reduced fatigue life, increased stress singularities at edges, difficulty in fabrication, and difficulty in the assembly, allowing the design of more complex and effective shapes [3, 6, 8, 9] that can efficiently work even in harsh environments, like in space applications or in surgical operations [6]. Thanks to these characteristics, they find practical applications in many fields of engineering, e.g. in the aerospace sector [2, 6, 10, 11], where compliant mechanisms are used to produce flexible hinges and to dampen the high level of vibrations during spacecraft take-off; in the medical sector [12, 13], where compliant mechanisms are used as surgical devices/tools with the intent to improve the compatibility with soft tissues; in piezoelectric energy harvesting applications [14], where compliant mechanisms can be practically combined with piezoelectric transducers to extract energy from the deformation of the mechanism; and in robotic applications [15], where compliant mechanisms are used to create force/motion amplifiers. However, the compliant mechanisms cannot be fabricated with classical industrial processes, but additive manufacturing procedures are needed to produce these devices [6, 16]. Such processes allow producing more complex shapes and designs which are inevitably accompanied by induced nonlinear behaviours, due to both the geometry and the material properties, as shown in many examples available in the literature [17, 18]. In this context, the knowledge about the nonlinear dynamic behaviour of 3D-printed complaint mechanisms is still very limited and needs to be better investigated by the scientific community. Thus, we propose the experimental investigation of a nonlinear compliant mechanism with a hexagonal profile which is produced by FDM (filament deposition modelling), a classical additive manufacturing procedure, and acts as a tuned-mass vibration absorber for a simple cantilever beam. Firstly, the nonlinear mechanical properties of the complaint mechanism are experimentally identified with the restoring force surface method C. Martinelli ( ) Naval Architecture, Ocean & Marine Engineering Department, University of Stratchlyde, Glasgow, UK e-mail: cristiano.martinelli@strath.ac.uk R. Avadhani · A. Cammarano James Watt School of Engineering, University of Glasgow, Glasgow, UK e-mail: 2696886a@student.gla.ac.uk; andrea.cammarano@glasgow.ac.uk © The Society for Experimental Mechanics, Inc. 2024 M. R. W. Brake et al. (eds.), Nonlinear Structures & Systems, Volume 1, Conference Proceedings of the Society for Experimental Mechanics Series, https://doi.org/10.1007/978-3-031-36999-5_30 229
RkJQdWJsaXNoZXIy MTMzNzEzMQ==