Six-Dimensional Compliance Analysis and Validation of Orthoplanar Springs

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Chen Qiu ◽  
Peng Qi ◽  
Hongbin Liu ◽  
Kaspar Althoefer ◽  
Jian S. Dai
Keyword(s):  
Finite Element ◽  
Parallel Mechanism ◽  
Fem Simulation ◽  
Analytical Models ◽  
Compliance Matrix ◽  
Out Of Plane ◽  
Continuum Manipulator ◽  
First Time ◽  
Good Agreement

This paper for the first time investigates the six-dimensional compliance characteristics of orthoplanar springs using a compliance-matrix based approach, and validates them with both finite element (FEM) simulation and experiments. The compliance matrix is developed by treating an orthoplanar spring as a parallel mechanism and is revealed to be diagonal. As a consequence, corresponding diagonal compliance elements are evaluated and analyzed in forms of their ratios, revealing that an orthoplanar spring not only has a large linear out-of-plane compliance but also has a large rotational bending compliance. Both FEM simulation and experiments were then conducted to validate the developed compliance matrix. In the FEM simulation, a total number of 30 types of planar-spring models were examined, followed by experiments that examined the typical side-type and radial-type planar springs, presenting a good agreement between the experiment results and analytical models. Further a planar-spring based continuum manipulator was developed to demonstrate the large-bending capability of its planar-spring modules.

Efficient Fatigue Testing of Tubular Joints

2015 ◽  
Author(s):  
P. Thibaux ◽  
J. Van Wittenberghe ◽  
E. Van Pottelberg ◽  
M. Van Poucke ◽  
P. De Baets ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Fatigue Loading ◽  
Tubular Joints ◽  
Testing Method ◽  
Out Of Plane ◽  
Resonance Principle ◽  
Tubular Joint ◽  
The Cost ◽  
Good Agreement

Tubular joints are intensively used in off-shore structures for shallow waters. Depending on the sea conditions and the type of structure, the design can be fatigue driven. This is particularly the case for off-shore wind turbines, where turbulences are generating a fatigue loading. Any improvement of the fatigue performance of the tubular joint would be beneficial to reduce the weight and the cost of the structure. To assess efficiently the fatigue resistance of the tubular joint, a testing method has been developed based on the resonance principle. The complete circumference of the welded joint can be loaded, successively in the in-plane and out-of-plane modes at a frequency close to 20Hz. Finite element computations were used to investigate the feasibility of the concept. Then, an X-node was made and successfully tested to investigate the stress distribution along the weld. The experimental results were compared with finite element computations, giving a good agreement.

scholarly journals Out-of-Plane Vibration of Curved Uniform and Tapered Beams with Additional Mass

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hamdi Alper Özyiğit ◽  
Mehmet Yetmez ◽  
Utku Uzun
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Variable Cross ◽  
Additional Mass ◽  
Inertia Effects ◽  
Tapered Beam ◽  
Out Of Plane ◽  
Good Agreement

As there is a gap in literature about out-of-plane vibrations of curved and variable cross-sectioned beams, the aim of this study is to analyze the free out-of-plane vibrations of curved beams which are symmetrically and nonsymmetrically tapered. Out-of-plane free vibration of curved uniform and tapered beams with additional mass is also investigated. Finite element method is used for all analyses. Curvature type is assumed to be circular. For the different boundary conditions, natural frequencies of both symmetrical and unsymmetrical tapered beams are given together with that of uniform tapered beam. Bending, torsional, and rotary inertia effects are considered with respect to no-shear effect. Variations of natural frequencies with additional mass and the mass location are examined. Results are given in tabular form. It is concluded that (i) for the uniform tapered beam there is a good agreement between the results of this study and that of literature and (ii) for the symmetrical curved tapered beam there is also a good agreement between the results of this study and that of a finite element model by using MSC.Marc. Results of out-of-plane free vibration of symmetrically tapered beams for specified boundary conditions are addressed.

FEM Analysis for the Influence of Manufacturing Process Defects on Dynamic Behavior of Thin Chromium Microbeam

2014 ◽  
Vol 548-549 ◽  
pp. 958-962 ◽  
Author(s):  
H. Bourouina ◽  
R. Yahiaoui ◽  
B.Y. Majlis ◽  
A. Hassein-Bey ◽  
M.E.A. Benamar ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Behavior ◽  
Manufacturing Process ◽  
Fem Simulation ◽  
Fem Analysis ◽  
Analytical Models ◽  
3D Fem ◽  
Thin Chromium ◽  
Technological Defects

This paper identifies and investigates the influence of technological defects of manufacturing process on the dynamic behavior of thin chromium microbeam. The analytical models will be analyzed and corrected using finite element method (FEM) to determine their validity under influence of technological defects. A semi-analytical model will be proposed for the extraction of corrective factors from 3D FEM simulation of dynamic behavior of microbeam. Final results indicate that the correction of technological defects is very significant for Cr microbeam 80x2x0.95μm3. In other hand, the corrected value of Young’s modulus is very close to the experimental results and it is about 279.1GPa.

Benchmark Investigation of Welding-Induced Buckling and Its Critical Condition During Thin Plate Butt Welding

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Jiangchao Wang ◽  
Bin Yi
Keyword(s):  
Finite Element ◽  
Thin Plate ◽  
Measurement Data ◽  
Characteristic Parameter ◽  
Welding Distortion ◽  
Butt Welding ◽  
Buckling Behavior ◽  
Out Of Plane ◽  
Inherent Deformation ◽  
Good Agreement

Welding-induced buckling is a special type of welding distortion occurring during thin plate butt welding and was investigated using both experimental and computational approaches for this benchmark investigation. In addition, the characteristic parameter and its magnitude for the occurrence of welding-induced buckling were also presented. Fundamental theories of the inherent deformation, finite strains, and eigenvalues of the structure stiffness matrix were considered to investigate welding-induced buckling. A series of experiments on thin plate butt welding with different heat inputs were conducted, and buckling behavior was observed from the deformed shape and the distribution of out-of-plane welding distortion. Transient nonlinear thermal elastic–plastic finite element (TEP FE) and elastic finite element (FE) analyses were conducted to predict welding-induced buckling, and the results were in good agreement with the measurement data. Criteria for the occurrence of welding-induced buckling were proposed and discussed. Inherent deformation was considered as a characteristic parameter of buckling behavior during welding, and its critical magnitude was calculated using a loading incremental method and eigenvalue analysis with good agreement.

scholarly journals Dynamics Studies of Nitrogen Interstitial in GaN from Ab Initio Calculations

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3627
Author(s):  
Huan He ◽  
Wenbo Liu ◽  
Pengbo Zhang ◽  
Wenlong Liao ◽  
Dayin Tong ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Separation Distance ◽  
Semiconductor Materials ◽  
Stable Configuration ◽  
Anisotropic Behavior ◽  
Out Of Plane ◽  
First Time ◽  
Good Agreement

Understanding the properties of defects is crucial to design higher performance semiconductor materials because they influence the electronic and optical properties significantly. Using ab initio calculations, the dynamics properties of nitrogen interstitial in GaN material, including the configuration, migration, and interaction with vacancy were systematically investigated in the present work. By introducing different sites of foreign nitrogen atom, the most stable configuration of nitrogen interstitial was calculated to show a threefold symmetry in each layer and different charge states were characterized, respectively. In the researches of migration, two migration paths, in-plane and out-of-plane, were considered. With regards to the in-plane migration, an intermediated rotation process was observed first time. Due to this rotation behavior, two different barriers were demonstrated to reveal that the migration is an anisotropic behavior. Additionally, charged nitrogen Frenkel pair was found to be a relatively stable defect complex and its well separation distance was about 3.9 Å. Part of our results are in good agreement with the experimental results, and our work provides underlying insights of the identification and dynamics of nitrogen interstitial in GaN material. This study of defects in GaN material is useful to establish a more complete theory and improve the performance of GaN-based devices.

FEM Simulation of Multipass Shape Rolling Processes

2010 ◽  
Vol 148-149 ◽  
pp. 1-6 ◽  
Author(s):  
Hai Liang Yu ◽  
Xiang Hua Liu
Keyword(s):  
Finite Element ◽  
Deformation Behavior ◽  
Fem Simulation ◽  
Element Model ◽  
Rolling Process ◽  
Pure Lead ◽  
Shape Rolling ◽  
First Pass ◽  
H Beam ◽  
Good Agreement

The updating geometric method was proposed to simulate the deformation behavior of workpiece during multipass shape rolling by using finite element method. Firstly, establish and solve the finite element model of the first pass shape rolling process, then update the geometric shape of workpiece after the first pass and delete rolls of the first pass, establish and mesh rolls of the second pass, modify the boundaries and material parameters of workpiece, and solve its deformation behavior during the second pass shape rolling. With the same steps, its deformation behavior during the following passes rolling could be solved. The method was applied to simulate the deformation behavior of a cube workpiece during six-pass H-beam rolling with split-rolling, and its shapes after every pass rolling process were obtained. Experiments on the deformation behavior of slab during multipass rolling were carried out by using pure lead in an experimental mill. The calculated results are in good agreement with the experimental ones.

Multistage Blisk and Large Mistuning Modeling Using Fourier Constraint Modes and PRIME

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Eric Kurstak ◽  
Kiran D'Souza
Keyword(s):  
Finite Element ◽  
Reduced Order Model ◽  
Degree Of Freedom ◽  
Order Model ◽  
Modal Expansion ◽  
Reduced Order ◽  
Multistage System ◽  
Computationally Expensive ◽  
First Time ◽  
Good Agreement

Current efforts to model multistage turbomachinery systems rely on calculating independent constraint modes for each degree-of-freedom (DOF) on the boundary between stages. While this approach works, it is computationally expensive to calculate all the required constraint modes. This paper presents a new way to calculate a reduced set of constraint modes referred to as Fourier constraint modes (FCMs). These FCMs greatly reduce the number of computations required to construct a multistage reduced order model (ROM). The FCM method can also be integrated readily with the component mode mistuning (CMM) method to handle small mistuning and the pristine rogue interface modal expansion (PRIME) method to handle large and/or geometric mistuning. These methods all use sector-level models and calculations, which make them very efficient. This paper demonstrates the efficiency of the FCM method on a multistage system that is tuned and, for the first time, creates a multistage ROM with large mistuning using only sector-level quantities and calculations. The results of the multistage ROM for the tuned and large mistuning cases are compared with full finite element results and are found in good agreement.

Confined masonry walls subjected to combined axial loads and out-of-plane uniform pressures

2012 ◽  
Vol 39 (4) ◽  
pp. 439-447 ◽  
Author(s):  
Jorge Varela-Rivera ◽  
Manuel Polanco-May ◽  
Luis Fernandez-Baqueiro ◽  
Eric I. Moreno
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Axial Load ◽  
Analytical Models ◽  
Maximum Pressure ◽  
Masonry Walls ◽  
The Finite Element Method ◽  
Axial Loads ◽  
Confined Masonry ◽  
Out Of Plane

This paper presents the results of a study on the behavior of three full-scale confined masonry walls subjected to combined axial loads and out-of-plane uniform pressures. The variable studied was the wall axial load. Analytical models were developed to predict out-of-plane cracking and maximum pressures. The former was predicted using the finite element method and the latter using the spring-strut method. This last method was modified to include the effect of the wall axial load. Experimental cracking and maximum pressures were compared with those obtained from analytical models. Based on the experimental results, it was concluded that as the axial load increases, the out-of-plane maximum pressure also increases. However, this latter value is limited by crushing of the masonry. By comparing experimental and analytical results, it was concluded that the out-of-plane cracking and maximum pressures are in general well predicted by the analytical models developed in this work.

The Through-Thickness Compressive Strength of a Composite Sandwich Panel With a Hierarchical Square Honeycomb Sandwich Core

2009 ◽  
Vol 76 (6) ◽  
Author(s):  
F. Côté ◽  
B. P. Russell ◽  
V. S. Deshpande ◽  
N. A. Fleck
Keyword(s):  
Finite Element ◽  
Compressive Strength ◽  
Sandwich Panel ◽  
Analytical Models ◽  
Composite Sandwich ◽  
Hierarchical Topology ◽  
Collapse Mechanisms ◽  
Strength Based ◽  
Out Of Plane ◽  
Plane Compression

Sandwich panels with aluminum alloy face sheets and a hierarchical composite square honeycomb core have been manufactured and tested in out-of-plane compression. The prismatic direction of the square honeycomb is aligned with the normal of the overall sandwich panel. The cell walls of the honeycomb comprise sandwich plates made from glass fiber/epoxy composite faces and a polymethacrylimide foam core. Analytical models are presented for the compressive strength based on three possible collapse mechanisms: elastic buckling of the sandwich walls of the honeycomb, elastic wrinkling, and plastic microbuckling of the faces of the honeycomb. Finite element calculations confirm the validity of the analytical expressions for the perfect structure, but in order for the finite element simulations to achieve close agreement with the measured strengths it is necessary to include geometric imperfections in the simulations. Comparison of the compressive strength of the hierarchical honeycombs with that of monolithic composite cores shows a substantial increase in performance by using the hierarchical topology.

Stress and Strength of free-standing 2-dimensional tetrahedral amorphous carbon bridge arrays

2003 ◽  
Vol 795 ◽  
Author(s):  
Daniel H.C. Chua ◽  
T. H. Tsai ◽  
W. I. Milne ◽  
D. Sheeja ◽  
B. K. Tay
Keyword(s):  
Amorphous Carbon ◽  
Fem Simulation ◽  
Vacuum Arc ◽  
Vertical Force ◽  
Free Standing ◽  
Tetrahedral Amorphous Carbon ◽  
Length Width ◽  
Filtered Cathodic Vacuum Arc ◽  
First Time ◽  
Good Agreement

ABSTRACTThe fabrication of ultrathin (25nm) 2-dimensional free-standing arrays of tetrahedral amorphous Carbon (ta-C) microbridges is reported for the first time. The ta-C films were deposited by a Filtered Cathodic Vacuum Arc (FCVA) deposition system where the sp3 content in the film was measured to be in excess of 90% by high resolution XPS. Continuous arrays of free standing taC bridges whose length/width ratios ranged from 1:1 to 12:1 were successfully fabricated while maintaining the same thickness. Due to the naturally high compressive stress of ta-C films, the buckling of films was perpendicular to the length of the beam. The displacement of curvature obtained was in good agreement with FEM simulation results. Moreover, the curvature or arch of these ultrathin films, coupled with a high Young's modulus (750GPa) and Hardness (60GPa), meant they could withstand a vertical force in excess of 8000μN without breaking.

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