Loading...

A Layerwise Dynamic Non-Linear Formulation for Multi-Layered Panels in the Presence of Viscoelastic Layer and Sma Wires

Khorasani, Reza | 2020

715 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53701 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Hosseini Kordkheili, Ali
  7. Abstract:
  8. This thesis aims to introduce a numerical method for investigating the appropriate arrangement of visco-pseudo-elastic dampers applicable to shell and plate structures under large deformation. These passive dampers are considered as viscoelastic layers and discrete shape memory alloy (SMA) wires in which this combination improves their overall efficiency and reduces their drawbacks. Also, the main advantages of these dampers are discussed during some illustrative problems. The current finite element formulation is based on an incremental updated Lagrangian (UL) approach along with the Newmark's integration technique. In the layerwise shell element, the Mindlin-Reissner theory is adopted in each layer and displacement field is described through thickness based on zig-zag theory. This element has eight nodes on its mid layer. As well, in addition to three translational and two rotational degrees of freedom per node, the upper and lower layers are allowed to rotate independently relative to their neighbor layers. Thus, the damping effect of the viscoelastic core could be well described within the shear deformable displacement field. The viscoelastic constitutive model which is used to define the behavior of the core, comes from the Riesz theorem and the corresponding creep functions are estimated using Dirichlet-Prony series. Also, the viscoelastic deferred strain is derived in an appropriate incremental form using the state variables. The SMA constitutive model is adopted and developed based on carried out experimental tests on a Ni-rich Nitinol alloy samples. These tests involve calorimetry and various tensile tests using environmental chamber. Pseudoelastic, pseudoplastic, strain recovery and de-twinning phenomena are perceived experimentally. The presented model characterizes pseudoelastic response of shape memory alloys and the Martensite-Austenite transformations. A nonlinear FE program is developed to assess the proposed procedure. The obtained numerical results correlate well with the prior studies. The results demonstrate that quick vibration mitigation may be possible using visco-pseudo-elastic dampers
  9. Keywords:
  10. Viscoelastic Behavior ; Experimental Test ; Constitutive Model ; Shape Memory Alloy ; Viscoelastic Damper ; Nonlinear Finite Element Analysis ; Large Deformation ; Layer-Wise Sandwich Shell Element ; Visco-Pseudo-Elastic Dampers

 Digital Object List

 Bookmark

No TOC