scholarly journals Membrane Triangles with Drilling Degrees of Freedom

10.14311/624 ◽  
2004 ◽  
Vol 44 (5-6) ◽  
Author(s):  
P. Fajman
Keyword(s):  
Nonlinear Analysis ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Nonlinear Problems ◽  
Drilling Degrees Of Freedom ◽  
Plane Element ◽  
Linear And Nonlinear

An accurate triangular plane element with drilling degrees of freedom is shown in this paper. This element can be successfully used for solving linear and nonlinear problems. The main advantage of this element is that the stiffness matrix is obtained from pure deformations – elongations of the edges. This aproach is very suitable for nonlinear analysis, where the unbalanced forces can be obtained directly from elongations of edges. 

A New Rotation-Free Shell Formulation Using Exact Corotational Frame for Dynamic Analysis and Applications

2018 ◽  
Vol 13 (4) ◽  
Author(s):  
Jiabei Shi ◽  
Zhuyong Liu ◽  
Jiazhen Hong
Keyword(s):  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Nonlinear Behavior ◽  
Nonlinear Problems ◽  
Shell Element ◽  
Accurate Solution ◽  
Singular Problem ◽  
Local Frame ◽  
Nonlinear Part ◽  
Tangential Stiffness

Rotation-free shell formulations were proved to be an effective approach to speed up solving large-scaled problems. It reduces systems' degrees-of-freedom (DOF) and avoids shortages of using rotational DOF, such as singular problem and rotational interpolation. The rotation-free element can be extended for solving geometrically nonlinear problems using a corotational (CR) frame. However, its accuracy may be lost if the approach is used directly. Therefore, a new nonlinear rotation-free shell element is formulated to improve the accuracy of the local bending strain energy using a CR frame. The linear strain for bending is obtained by combining two re-derived elements, while the nonlinear part is deduced with the side rotation concept. Furthermore, a local frame is presented to correct the conventional local CR frame. An explicit tangential stiffness matrix is derived based on plane polar decomposition local frame. Simple elemental rotation tests show that the stiffness matrix and the proposed local frame are both correct. Several numerical examples and the application of drape simulations are given to verify the accuracy of nonlinear behavior of the presented element, and some of the results show that the presented method only requires few elements to obtain an accurate solution to the problem studied.

scholarly journals Partial Refactorization in Sparse Matrix Solution: A New Possibility for Faster Nonlinear Finite Element Analysis

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Qi Song ◽  
Pu Chen ◽  
Shuli Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Nonlinear Analysis ◽  
Degrees Of Freedom ◽  
Optimization Problems ◽  
Sparse Matrix ◽  
Nonlinear Problems ◽  
Local Change ◽  
Matrix Solution ◽  
Element Analysis

This paper proposes a partial refactorization for faster nonlinear analysis based on sparse matrix solution, which is nowadays the default solution choice in finite element analysis and can solve finite element models up to millions degrees of freedom. Among various fill-in’s reducing strategies for sparse matrix solution, the graph partition is in general the best in terms of resultant fill-ins and floating-point operations and furthermore produces a particular graph of sparse matrix that prevents local change of entries from wide spreading in factorization. Based on this feature, an explicit partial triangular refactorization with local change is efficiently constructed with limited additional storage requirement in row-sparse storage scheme. The partial refactorization of the changed stiffness matrix inherits a big percentage of the original factor and is carried out only on partial factor entries. The proposed method provides a new possibility for faster nonlinear analysis and is mainly suitable for material nonlinear problems and optimization problems. Compared to full factorization, it can significantly reduce the factorization time and can make nonlinear analysis more efficient.

scholarly journals Tuned Mass Damper Design for Slender Masonry Structures: A Framework for Linear and Nonlinear Analysis

2021 ◽  
Vol 11 (8) ◽  
pp. 3425
Author(s):  
Marco Zucca ◽  
Nicola Longarini ◽  
Marco Simoncelli ◽  
Aly Mousaad Aly
Keyword(s):  
Nonlinear Analysis ◽  
Linear Time ◽  
Design Procedure ◽  
Time History ◽  
Tuned Mass Damper ◽  
Second Phase ◽  
Masonry Structures ◽  
Base Shear ◽  
Mass Damper ◽  
Linear And Nonlinear

The paper presents a proposed framework to optimize the tuned mass damper (TMD) design, useful for seismic improvement of slender masonry structures. A historical masonry chimney located in northern Italy was considered to illustrate the proposed TMD design procedure and to evaluate the seismic performance of the system. The optimization process was subdivided into two fundamental phases. In the first phase, the main TMD parameters were defined starting from the dynamic behavior of the chimney by finite element modeling (FEM). A series of linear time-history analyses were carried out to point out the structural improvements in terms of top displacement, base shear, and bending moment. In the second phase, masonry's nonlinear behavior was considered, and a fiber model of the chimney was implemented. Pushover analyses were performed to obtain the capacity curve of the structure and to evaluate the performance of the TMD. The results of the linear and nonlinear analysis reveal the effectiveness of the proposed TMD design procedure for slender masonry structures.

OPTIMAL VELOCITY MODEL WITH RELATIVE VELOCITY

2006 ◽  
Vol 17 (01) ◽  
pp. 65-73 ◽  
Author(s):  
SHIRO SAWADA
Keyword(s):  
Nonlinear Analysis ◽  
Relative Velocity ◽  
Velocity Model ◽  
Fundamental Diagram ◽  
Optimal Velocity ◽  
Traffic Jam ◽  
Optimal Velocity Model ◽  
Linear And Nonlinear ◽  
The Stability ◽  
Good Agreement

The optimal velocity model which depends not only on the headway but also on the relative velocity is analyzed in detail. We investigate the effect of considering the relative velocity based on the linear and nonlinear analysis of the model. The linear stability analysis shows that the improvement in the stability of the traffic flow is obtained by taking into account the relative velocity. From the nonlinear analysis, the relative velocity dependence of the propagating kink solution for traffic jam is obtained. The relation between the headway and the velocity and the fundamental diagram are examined by numerical simulation. We find that the results by the linear and nonlinear analysis of the model are in good agreement with the numerical results.

Linear and Nonlinear Analysis of Additively Manufactured Material With Different Porosity Induced by Varying Material Printing Speed Using Guided Acoustic Waves

2021 ◽  
Author(s):  
SeHyuk Park ◽  
Hamad Alnuaimi ◽  
Anna Hayes ◽  
Madison Sitkiewicz ◽  
Umar Amjad ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Nonlinear Analysis ◽  
Lead Zirconate Titanate ◽  
Acoustic Waves ◽  
Scanning Speed ◽  
Lead Zirconate ◽  
Nonlinear Ultrasonic ◽  
Scan Speed ◽  
Linear And Nonlinear ◽  
Characterization Of Materials

Abstract Guided acoustic wave based techniques have been found to be very effective for damage detection, and both quantitative and qualitative characterization of materials. In this research, guided acoustic wave techniques are used for porosity evaluation of additively manufactured materials. A metal 3D printer, Concept Laser Mlab 200 R Cusing™, is used to manufacture 316L additively manufactured (AM) stainless steel specimens. Two levels of porosity are investigated in this study, which was controlled by a suitable combination of scan speed and laser power. The sample with lower level of porosity is obtained with a low scanning speed. Lead Zirconate Titanate (PZT) transducers are used to generate guided acoustic waves. The signal is excited and propagated through the specimens in a single sided transmission mode setup. Signal processing of the recorded signals for damage analysis involves both linear and nonlinear analyses. Linear ultrasonic parameters such as the time-of-flight and magnitude of the propagating waves are recorded. The nonlinear ultrasonic parameter, the Sideband Peak Count Index (SPC-I) is obtained by a newly developed nonlinear analysis technique. Results obtained for both specimens are analyzed and compared using both linear and nonlinear ultrasonic techniques. Finally, the effectiveness of SPC-I technique in monitoring porosity levels in AM specimens is discussed.

Study of the Stiffness Matrix of Preloaded Duplex Angular Contact Ball Bearings

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Shengye Lin ◽  
Shuyun Jiang
Keyword(s):  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Ball Bearing ◽  
Ball Bearings ◽  
Fixed Position ◽  
Angular Contact Ball Bearing ◽  
Face To Face ◽  
Radial Stiffness ◽  
Proposed Model ◽  
Stiffness Characteristics

This paper studies the stiffness characteristics of preloaded duplex angular contact ball bearings. First, a five degrees-of-freedom (5DOF) quasi-static model of the preloaded duplex angular contact ball bearing is established based on the Jones bearing model. Three bearing configurations (face-to-face, back-to-back, and tandem arrangements) and two preload mechanisms (constant pressure preload and fixed position preload) are included in the proposed model. Subsequently, the five-dimensional stiffness matrix of the preloaded duplex angular contact ball bearing is derived analytically. Then, an experimental setup is developed to measure the radial stiffness and the angular stiffness of duplex angular contact ball bearings. The simulated results match well with those from experiments, which prove the validity of the proposed model. Finally, the effects of bearing configuration, preload mechanism, and unloaded contact angle on the angular stiffness and the cross-coupling are studied systematically.

Sign in / Sign up

Export Citation Format

Share Document