Nonstationary pandom vibpation analysis of linear elastic structures with finite element method

1982 ◽  
Vol 3 (6) ◽  
pp. 817-826 ◽  
Author(s):  
Jin Wen-lu
2018 ◽  
Vol 30 (3) ◽  
pp. 416-437 ◽  
Author(s):  
Liming Zhou ◽  
Ming Li ◽  
Bingkun Chen ◽  
Feng Li ◽  
Xiaolin Li

In this article, an inhomogeneous cell-based smoothed finite element method (ICS-FEM) was proposed to overcome the over-stiffness of finite element method in calculating transient responses of functionally graded magneto-electro-elastic structures. The ICS-FEM equations were derived by introducing gradient smoothing technique into the standard finite element model; a close-to-exact system stiffness was also obtained. In addition, ICS-FEM could be carried out with user-defined sub-routines in the business software now available conveniently. In ICS-FEM, the parameters at Gaussian integration point were adopted directly in the creation of shape functions; the computation process is simplified, for the mapping procedure in standard finite element method is not required; this also gives permission to utilize poor quality elements and few mesh distortions during large deformation. Combining with the improved Newmark scheme, several numerical examples were used to prove the accuracy, convergence, and efficiency of ICS-FEM. Results showed that ICS-FEM could provide solutions with higher accuracy and reliability than finite element method in analyzing models with Rayleigh damping. Such method is also applied to complex structures such as typical micro-electro-mechanical system–based functionally graded magneto-electro-elastic energy harvester. Hence, ICS-FEM can be a powerful tool for transient problems of functionally graded magneto-electro-elastic models with damping which is of great value in designing intelligence structures.


2009 ◽  
Vol 46 (6) ◽  
pp. 627-638 ◽  
Author(s):  
Nainan P. Kurian ◽  
Syed J. Shah

A circular pile with helical blades is an old type of foundation, which has staged a comeback recently and is being used in a variety of situations. Most of the research on helical screw piles has been experimental or theoretical with the help of simplifying assumptions. The method of design adopted so far treats this pile as an annular plate, disregarding the intricacies of the geometry of the helix. It is only the versatility of the finite element method that can take into account the actual geometry of a spatial structure such as the helical blade at a microlevel. This is perhaps the first attempt at such an analysis to study the response of the helical screw pile within the elastic and nonlinear ranges. While the pile is linearly elastic, soil is considered both as a linear elastic medium and as an elastic–plastic medium following the Drucker–Prager constitutive model. Cases of smooth contact and frictional contact between soil and screw pile are also considered. Screw piles are studied under compressive, tensile, and lateral loading conditions. Moreover, their performance is compared with that of prismatic piles. A parametric study has also been attempted on some key geometrical features of the screw pile.


1999 ◽  
Vol 123 (3) ◽  
pp. 218-224 ◽  
Author(s):  
Cemal Basaran ◽  
Ying Zhao

Multi-layered stacks are commonly used in microelectronic packaging. Traditionally, these systems are designed using linear-elastic analysis either with analytical solutions or finite element method. Linear-elastic analysis for layered structures yields very conservative results due to stress singularity at the free edge. In this paper, it is shown that a damage mechanics based nonlinear analysis not just leads to a more realistic analysis but also provides more accurate stress distribution. In this paper these two approaches are compared. Moreover, mesh sensitivity of the finite element analysis in stack problems is studied. It is shown that the closed form and elastic finite element analyses can only be used for preliminary studies and elastic finite element method is highly mesh sensitive for this problem. In elastic analysis the stress singularity at the free edge makes mesh selection very difficult. Even when asymptotic analysis is used at the free edge, the results are very conservative compared to an inelastic analysis. Rate sensitive inelastic analysis does not suffer from the stress singularity and mesh sensitivity problems encountered in elastic analysis.


Sign in / Sign up

Export Citation Format

Share Document