Session: 07-19-01: Symposium on the Anniversary of the Timoshenko-Ehrenfest Beam Model and Other Refined Theories and Vibrations of Continuous Systems

Paper Number: 144209

144209 - Dynamic Analyses of Sandwich Structures Through Variable-Fidelity Beam Models 

Sandwich structures have become essential components in various industries due to their exceptional mechanical properties and versatility. These structures consist of a lightweight core material sandwiched between two outer layers, providing a unique combination of strength, stiffness, and weight reduction. While the concept of sandwich structures has been prevalent for centuries, recent advancements in materials and manufacturing techniques have revolutionized their applications across aerospace, automotive, marine, and construction industries. The significance of sandwich structures lies in their ability to enhance performance, optimize structural efficiency, and meet modern engineering requirements. A comprehensive understanding of the mechanics and behavior of the skins and the core is crucial for accurately analyzing sandwich structures. However, a current challenge is to provide designers with adequate methodologies and tools to design improved sandwich structures based on advanced knowledge of their global and local behavior. This requires effective testing, identification, control, and modeling of the structural performance.
The present work discusses some advances in the dynamic analysis of sandwich structures. Based on the Carrera Unified Formulation (CUF), geometrically linearized and full nonlinear governing equations are derived to investigate vibrations, transient responses, and dynamic instabilities of loaded and unloaded sandwich beam structures. In particular, 1D beam finite element models with variable kinematics were adopted. Both Equivalent Single Layer (ESL) models using Taylor expansions (TE) and Layerwise (LW) models adopting the Lagrange expansion (LE) are utilized. The equation of motion was derived using a total Lagrangian framework, which incorporates all terms of the Green-Lagrange strain tensor and the linear constitutive law in three dimensions. Thanks to the CUF and using all terms of the full Green-Lagrange (GL) strain tensor, the proposed methodology can detect simple and complex nonlinear phenomena, including those related to deep nonlinear regimes. Particular attention is given to characterizing the response of sandwich structures under various boundary and loading conditions, including mechanical or thermal loads and parametric excitations. Low kinematics models can be adopted whenever stable conditions exist with no loss of generality. In contrast, in the case of unstable regimes, and when the stress state is complex, high-order kinematics models and full displacement-strain relations must be used to describe vibrations.  The results, discussed and compared with commercial software solutions, demonstrate the excellent accuracy and reliability of the proposed numerical methodology. For evaluating static responses in sandwich beam-like structures, lower-order Equivalent-Single-Layer (ESL) models are suitable. However, to accurately investigate dynamic phenomena, higher-order Layerwise (LW) models must be employed. The dynamic instability characteristics of structures subjected to parametric excitations have been investigated. The method was revealed to be accurate and computationally efficient.

Presenting Author: Rodolfo Azzara Politecnico Di Torino

Presenting Author Biography: Rodolfo Azzara is an Aerospace Engineer working at Politecnico di Torino. He gained his BSc in Aerospace Engineering at the Politecnico di Torino in October 2016, presenting a thesis on additive manufacturing for aerospace. Afterward, he obtained an MSc from the same university in December 2018, with a thesis on the analysis and design of landing gear, lander, and docking phases through multibody simulations. Rodolfo started working at Politecnico di Torino in January 2019 under the supervision of Prof. Erasmo Carrera. He was involved in an international project dealing with ground vibration tests, flight tests, and flutter clearance. He was awarded his Ph.D. in Mechanical Engineering in March 2023, presenting a PhD Thesis on the nonlinear and linearized analysis of vibrations of loaded anisotropic beam, plate, and shell structures. From April 2023 to August 2023 he held a postdoctoral position at the Politecnico di Torino. In September 2023 he became an Assistant Professor at Politecnico di Torino. His current research project is about the development of advanced theories for the nonlinear static and dynamic analysis of non-rotating and rotating structures.

Authors:

Rodolfo Azzara Politecnico Di Torino
Matteo Filippi Politecnico di Torino
Erasmo Carrera Politecnico di Torino