scholarly journals Geometrical Nonlinear Analysis of Slender Micro Arch-Beams Pulled by Magnetic Loadings

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Magnetic Force ◽  
Beam Theory ◽  
Shallow Arch ◽  
Air Gaps ◽  
Beam Elements ◽  
Straight Beam ◽  
Geometrical Nonlinear ◽  
Structure Equations ◽  
Path Dependent ◽  
Nonlinear Deformations

In this study, a nonlinear model of micro arch-beams under the action of electrostatic loadings with an initial air gap is presented. Based on the well-developed 3D beam theory proposed by Yang and Kuo [4], the arch beam is modelled as a series of uniform straight beam elements and the pull-in magnetic force is simulated as an electric-induced force by an electrode lying. Then the nonlinear structural analysis of snap-through and pull-in stability for a simply supported shallow arch subjected to a concentrated electrostatic loading will be investigated. To tackle the path-dependent features of electric forces due to presence of air gaps and nonlinear deformations, this study regards the electric forces as pseudo-forces acting at the arch-beam and solves the structure equations using an incremental-iterative procedure. From the numerical results, the present approach demonstrates that the micro-arch beam has the capacity to withstand further electrostatic loading after the snapthrough jump.

A new simplified method for anti-symmetric mode in-plane vibrations of frame structures with column cracks

2016 ◽  
Vol 24 (24) ◽  
pp. 5794-5810 ◽  
Author(s):  
Kemal Mazanoglu ◽  
Elif C Kandemir-Mazanoglu
Keyword(s):  
Beam Theory ◽  
Equivalent Model ◽  
Frame Structures ◽  
Symmetric Mode ◽  
Lumped Mass ◽  
Beam Elements ◽  
Local Flexibility ◽  
Mode Vibration ◽  
Frame Systems ◽  
Lumped Masses

This paper is on the natural frequency and mode shape computation of frame structures with column cracks. First, a model of intact frame structures is built to perform vibration analysis. Beam elements are considered as lumped masses and rotational springs at the storey levels of frames. Equivalent model of columns and lumped mass-stiffness effects of beams have been combined to carry out continuous solution for the anti-symmetric mode in-plane vibrations of frames. In addition, frame systems with multiple column cracks are analyzed in terms of anti-symmetric mode vibration characteristics. Cracks are considered as massless rotational springs in compliance with the local flexibility model. Compatibility and continuity conditions are satisfied at crack and storey locations of the equivalent column, modeled using the Euler–Bernoulli beam theory. The proposed method is tested for single-storey single- and multi-bay, H-type and double-storey single-bay frame systems with intact and cracked columns. Results are validated by those given in the current literature and/or obtained by the finite element analyses.

A Pipe Bend Subject to a Uniformly Distributed Radial Force

2012 ◽  
Author(s):  
Joseph M. Mazzeo
Keyword(s):  
Radial Force ◽  
Piping System ◽  
Curved Beam ◽  
Pipe Bend ◽  
Beam Elements ◽  
Straight Beam ◽  
Uniform Cross Section ◽  
Single Force ◽  
Direct Stiffness ◽  
Small Deformations

The effects of a distributed radial load on an elbow or bend within a piping system, caused by large changes in momentum due to fluid flow, are often represented by a single force. The method presented here will result in more accurate results. In this paper, equations are derived to predict deformations of a pipe bend or curved beam cantilever at its free end due to a uniformly distributed radial force. Assuming isotropic, linearly elastic materials of uniform cross section, uniform bend radius, and small deformations, equations are derived using Castigliano’s theorem. Deformation due to shear and axial stresses is also considered. Derived equations are validated through a case example which compares them to a model consisting of a number of straight beam elements assembled to model a curved beam. The example demonstrates that free end deformations can be integrated into a piping analysis program by using the direct stiffness method in order to obtain the resulting displacements, forces, and moments that result from restraint of the bend due to the stiffness of the attached pipe.

Modeling and Experimentation of a Ribbed Caudal Fin for Aquatic Robots

2017 ◽  
Author(s):  
Oscar Rios ◽  
Ardavan Amini ◽  
Hidenori Murakami
Keyword(s):  
Large Deformation ◽  
Beam Theory ◽  
Fe Model ◽  
Beam Model ◽  
Caudal Fin ◽  
Nonlinear Beam ◽  
Beam Elements ◽  
Side Walls ◽  
Thin Beams ◽  
Shear Deformable

Presented in this study is a mathematical model and preliminary experimental results of a ribbed caudal fin to be used in an aquatic robot. The ribbed caudal fin is comprised of two thin beams separated by ribbed sectionals as it tapers towards the fin. By oscillating the ribbed caudal fin, the aquatic robot can achieve forward propulsion and maneuver around its environment. The fully enclosed system allows for the aquatic robot to have very little effect on marine life and fully blend into its respective environment. Because of these advantages, there are many applications including surveillance, sensing, and detection. Because the caudal fin actuator has very thin side walls, Kirchhoff-Love’s large deformation beam theory is applicable for the large deformation of the fish-fin actuator. In the model, it is critical to accurately model the curvature of beams. To this end, C1 beam elements for thin beams are developed by specializing the shear-deformable beam elements, developed by the authors, based upon Reissner’s shear-deformable nonlinear beam model. Furthermore, preliminary experiments on the ribbed fin are presented to supplement the FE model.

Optimized Solutions to Control Lateral Buckling of Pipelines With Snaked-Lay: Theoretical and Numerical Studies

2007 ◽  
Author(s):  
Jiong Guan ◽  
Per R. Nystro̸m ◽  
Hans F. Hansen
Keyword(s):  
Finite Strain ◽  
Beam Theory ◽  
Fe Analysis ◽  
Hostile Environment ◽  
Lateral Buckling ◽  
Numerical Studies ◽  
High Pressure High Temperature ◽  
Straight Beam ◽  
Offshore Development ◽  
Subsea Pipelines

Due to the offshore development moving to a more hostile environment, thermal buckling becomes an important issue needed to be considered for HPHT (high-pressure high temperature) subsea pipelines design. In order to control the lateral buckling, the snaked lay method is investigated theoretically and numerically. The buckling mechanisms of the curved beam are studied with methods considering the finite strain and simplified straight beam theory, respectively. The differences between the two methods are found to be negligible when the radius of curve is larger than a certain value. Detailed FE analysis results are given for the buckle behavior of a snaked-lay pipeline. The method to control the subsea pipeline lateral buckling is discussed and followed by a design example.

In Plane Radial Vibration of Uncracked and Cracked Circular Curved Beams Subjected to Moving Loads

2021 ◽  
pp. 2150146
Author(s):  
Jatin Poojary ◽  
Sankar Kumar Roy
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Real Life ◽  
Beam Theory ◽  
Point Of View ◽  
Curved Beam ◽  
Moving Loads ◽  
Curved Beams ◽  
Beam Elements ◽  
Curved Beam Element

The dynamic response of structures subjected to moving load is a subject of great importance from a practical point of view. In this work, the in-plane dynamic response of a cracked isotropic circular curved beam subjected to moving loads is investigated using the finite element method. The curved beam is modeled using curved beam elements, which is developed based on the Timoshenko beam theory. Furthermore, a cracked curved beam element is developed to incorporate the presence of cracks in the structure. The effect of moving load speed, depth, and the location of the crack on the dynamic response of the beam is investigated. The outcome of the work can be useful in the study of real-life moving load problems like bridges and railways and also in the field of condition monitoring using moving loads.

scholarly journals Mechanical models in computational form finding of bending-active structures

2018 ◽  
Vol 33 (2) ◽  
pp. 86-97 ◽  
Author(s):  
Carlos Lázaro ◽  
Juan Bessini ◽  
Salvador Monleón
Keyword(s):  
Three Dimensional ◽  
Beam Theory ◽  
Task Type ◽  
Degree Of Freedom ◽  
Complex Nature ◽  
Dynamic Relaxation ◽  
Form Finding ◽  
Beam Elements ◽  
Active Structures ◽  
Computational Form

This article reviews the different aspects involved in computational form finding of bending-active structures based on the dynamic relaxation technique. Dynamic relaxation has been applied to form-finding problems of bending-active structures in a number of references. Due to the complex nature of large spatial deformations of flexible beams, the implementation of suitable mechanical beam models in the dynamic relaxation algorithm is a non-trivial task. Type of discretization and underlying beam theory have been identified as key aspects for numerical implementations. References can be classified into two groups depending on the selected discretization: finite-difference-like and finite-element-like. The first group includes 3- and 4-degree-of-freedom implementations based on increasingly complex beam models. The second gathers 6-degree-of-freedom discretizations based on co-rotational three-dimensional Kirchhoff–Love beam elements and geometrically exact Reissner–Simo beam elements. After reviewing and comparing implementation details, the advantages and drawbacks of each group have been discussed, and open aspects for future work have been pointed out.

Finite Element Stability Analysis of a Glulam Dome

1992 ◽  
Vol 7 (4) ◽  
pp. 353-361 ◽  
Author(s):  
S.M. Holzer ◽  
C.H. Wu ◽  
J. Tissaoui
Keyword(s):  
Finite Element ◽  
Joint Stiffness ◽  
Buckling Load ◽  
Nonlinear Method ◽  
Beam Elements ◽  
Eigenvalue Method ◽  
Straight Beam ◽  
Glued Laminated Timber ◽  
The Status ◽  
The Stability

The paper centres on stability investigations of a glued-laminated timber (glulam) dome under several snow load conditions. The dome consists of a triangulated network of curved glulam beams, a decking supported by curved purlins, and a steel tension ring. The dome is represented by two different models. The first model is a rigid-jointed space frame composed of curved beam elements. The second model consists of straight beam elements, with rigid or flexible joints, and a bracing to simulate the lateral support of the beams provided by the decking. Two finite element methods are presented and used in the analyses: A nonlinear method that computes the buckling load and a combined nonlinear/linear eigenvalue method that provides estimates of the buckling load. The results presented include buckling pressures, buckling modes, effects of joint stiffness and bracing on the stability of the dome, and the status of the material prior to buckling.

scholarly journals Linear Buckling Analysis of Perforated Cold-Formed Steel Storage Rack Columns by Means of the Generalised Beam Theory

2018 ◽  
Vol 18 (01) ◽  
pp. 1850004 ◽  
Author(s):  
M. Casafont ◽  
J. Bonada ◽  
M. M. Pastor ◽  
F. Roure ◽  
A. Susín
Keyword(s):  
Finite Element ◽  
Beam Theory ◽  
Element Discretization ◽  
Buckling Loads ◽  
Beam Elements ◽  
Linear Buckling ◽  
Finite Element Procedure ◽  
Cold Formed Steel ◽  
Shell Finite Element ◽  
Deformation Modes

The investigation attempts to adapt a beam finite element procedure based on the Generalized Beam Theory (GBT) to the analysis of perforated columns. The presence of perforations is taken into account through the use of two beam elements with different properties for the non-perforated and perforated parts of the member. Each part is meshed with its corresponding finite element and, afterwards, they are linked by means of constraint equations. Linear buckling analyses on steel storage rack columns are carried out to demonstrate how the proposed procedure should be applied. Some practical issues are discussed, such as the GBT deformation modes to be included in the analyses, or the optimum finite element discretization. The resulting buckling loads are validated by comparison with the values obtained in analyses performed using shell finite element models. Finally, it is verified that the buckling loads produced with the proposed method are rather accurate.

scholarly journals THE EXPERIMENTAL RESEARCHES OF REINFORCED CONCRETE I-BEAM ELEMENTS WITH NORMAL CRACKS WHEN TURNING

2019 ◽  
Vol 2 (53) ◽  
pp. 171-176
Author(s):  
Olga Orlova
Keyword(s):  
Reinforced Concrete ◽  
Twist Angle ◽  
Longitudinal Reinforcement ◽  
External Torque ◽  
Beam Elements ◽  
The Difference ◽  
The Moment ◽  
Nonlinear Deformations ◽  
Experimental Researches ◽  
Concrete Elements

The data of experimental researches of the rigidity of reinforced concrete I-beam elements with normal cracks at the action on them of the twisting moment have resulted in this paper. It is shown that the dependence "torque-twist angle" is almost linear. Significant nonlinear deformations appear in the last stages of loading before failure. Therefore at normative torques, it is recommended to consider the work of reinforced concrete elements of the I-beam cross-section with normal cracks linear. It is shown that the presence of longitudinal reinforcement affects the strength and rigidity of beams with normal cracks. Quite a large part of the external torque is perceived by the pin forces in the longitudinal reinforcement. The difference between the external torque and the moment of the pin forces in the armature is perceived by the upper shelf of the I-beam element. In the absence of longitudinal reinforcement, the upper shelf can collapse at loads much smaller than the destructive load of beams with longitudinal reinforcement.

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