Static Analysis of an Inverted Planetary Roller Screw Mechanism

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Folly Abevi ◽  
Alain Daidie ◽  
Michel Chaussumier ◽  
Stéphane Orieux
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Analytical Models ◽  
Axial Stiffness ◽  
Static Behavior ◽  
Fe Method ◽  
Heavy Load ◽  
Positioning Errors ◽  
Roller Screw ◽  
Three Dimensional Finite Element

The paper examines the static behavior of the inverted planetary roller screw (PRS) through numerical and experimental studies. The numerical analysis of the inverted PRS is first presented to capture the global and local deformations in different configurations. Using a three-dimensional finite element (3D FE) method, a sectorial model of the mechanism is built involving an entire roller. The model describes the static behavior of the system under a heavy load and shows the state of the contacts and the in-depth stress zones. The current work also investigates the axial stiffness (AS) and the load distribution (LD) under both compressive and tensile loadings. It is shown that the LDs are not the same at each contact interface of the roller and that they depend on the configuration of the system. Also, the nut is less stressed than the screw shaft because of their contact curvatures. In parallel, complementary experiments are carried out to measure the axial deflection of the screw shaft and the rollers in five cases with different numbers of rollers. In each situation, the mechanism is under the same equivalent axial and static load. The tests reveal that rollers do not have the same behavior, the difference certainly being due to manufacturing and positioning errors that directly affect the number of effective contacts in the device. This stresses the fact that the external load is unequally shared over rollers and contacting threads. By introducing the notion of an equivalent roller, the results are used to validate the previous numerical model of an inverted PRS. As they provide a better understanding of the inverted PRS, these investigations are useful to improve the existing analytical models of the device.

Static Load Distribution and Axial Stiffness in a Planetary Roller Screw Mechanism

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Folly Abevi ◽  
Alain Daidie ◽  
Michel Chaussumier ◽  
Marc Sartor
Keyword(s):  
Load Distribution ◽  
Static Load ◽  
Computing Time ◽  
Three Dimensional ◽  
External Loading ◽  
Axial Stiffness ◽  
Fe Model ◽  
Roller Screw ◽  
Three Dimensional Finite Element ◽  
The Impact

In this paper, an original approach is proposed to calculate the static load distribution and the axial stiffness of a planetary roller screw (PRS) mechanism. Assuming that the external loading is shared equally over an arbitrary number of rollers, only a sector of the system is represented to save on computing time. The approach consists in using a structure of bars, beams, and nonlinear springs to model the different components of the mechanism and their interactions. This nonlinear model describes the details of the mechanism and captures the shape of the nut as well as the bending deformation of the roller. All materials are assumed to operate in the elastic range. The load distribution and the axial stiffness are determined in three specific configurations of the system for both compressive and tensile loads. Further, the influence of the shape of the nut is studied in the case of the inverted PRS. The results obtained from this approach are also compared to those computed with a three-dimensional finite-element (3D FE) model. Finally, since the calculations appear to be very accurate, a parametric study is conducted to show the impact of the bending of the roller on the load distribution.

Numerical Modeling of Tube Hydropiercing Using Phenomenological and Micro-Mechanical Damage Criteria

2013 ◽  
Vol 549 ◽  
pp. 172-179 ◽  
Author(s):  
Amir Hassannejadasl ◽  
Daniel E. Green
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Equivalent Plastic Strain ◽  
Mechanical Damage ◽  
High Strength ◽  
Dimensional Finite Element ◽  
Steel Dp600 ◽  
Three Dimensional Finite Element ◽  
Jc Model ◽  
Damage Criteria

Hydropiercing is an efficient way of piercing holes in mass produced hydroformed parts with complex geometries. By driving piercing punches radially into a hydroformed and fully pressurized tube, holes will be pierced and extruded into the tube-wall. Recent experimental studies have shown that the formability of advanced high strength steel (AHSS) tubes can be increased with the application of internal pressure. In this study, three-dimensional finite element simulations of a tube hydropiercing process of a dual phase steel (DP600) were performed in LS-DYNA, using phenomenological, micromechanical and combined damage criteria. Damage was included in the numerical analysis by applying constant equivalent plastic strain (CEPS), the Gurson-Tvergaard-Needleman (GTN), and the Extended GTN (GTN+JC) model. In order to calibrate the parameters in each model, a specialized hole-piercing fixture was designed and piercing tests were carried out on non-pressurized tube specimens. Of the various ductile fracture criteria, the results predicted with the GTN+JC model, such as the punch load-displacement, the roll-over depth, and the quality of the clearance zone correlated the best with the experimental data.

A Biomechanical Model of Lumbar Spine

2000 ◽  
Author(s):  
Subramanya Uppala ◽  
Robert X. Gao ◽  
Scott Cowan ◽  
K. Francis Lee
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Biomechanical Model ◽  
Element Model ◽  
Fe Model ◽  
Flexion Extension ◽  
Cortical Shell ◽  
Three Dimensional Finite Element

Abstract The strength and stability of the lumbar spine are determined not only by the bone and muscles, but also by the visco-elastic structures and the interplay between the different components of the spine, such as ligaments, capsules, annulus fibrosis, and articular cartilage. In this paper we present a non-linear three-dimensional Finite Element model of the lumbar spine. Specifically, a three-dimensional FE model of the L4-5 one-motion segment/2 vertebrae was developed. The cortical shell and the cancellous bone of the vertebral body were modeled as 3D isoparametric eight-nodal elements. Finite element models of spinal injuries with fixation devices are also developed. The deformations across the different sections of the spine are observed under the application of axial compression, flexion/extension, and lateral bending. The developed FE models provided input to both the fixture design and experimental studies.

Examination of Response of a Skewed Steel Bridge Superstructure During Deck Placement

2003 ◽  
Vol 1845 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Elizabeth K. Norton ◽  
Daniel G. Linzell ◽  
Jeffrey A. Laman
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Analytical Models ◽  
Levels Of Analysis ◽  
Steel Bridge ◽  
Bridge Superstructure ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Skewed Bridge

The response of a 74.45-m (244-ft 0-in.) skewed bridge to the placement of the concrete deck was monitored to compare measured and predicted behavior. This comparison was completed to ( a) determine theoretical deflections and rotations with analytical models for comparison to actual deformations monitored during construction; ( b) compare the results of various levels of analysis to determine the adequacy of the methods; and ( c) examine variations on the concrete placement sequence to determine the most efficient deck placement methods. Two levels of analysis were used to achieve the objectives. Level 1 was a two-dimensional finite element grillage model analyzed with STAAD/Pro. Level 2 was a three-dimensional finite element model analyzed with SAP2000. These studies are discussed and findings are presented.

scholarly journals Theoretical and Finite Element Modeling of Fine Kirschner Wires in Ilizarov External Fixator

2010 ◽  
Vol 4 (3) ◽  
Author(s):  
A. R. Zamani ◽  
S. O. Oyadiji
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Kirschner Wires ◽  
Fe Method ◽  
Mathematical Solution ◽  
New Exact Solutions ◽  
Ilizarov Apparatus ◽  
Dimensional Finite Element ◽  
Experimental Findings ◽  
Three Dimensional Finite Element

The mechanical behavior of the transosseous elements is a defining factor in the overall stiffness, stability, and reliability of an external fixation system. Mechanics involving the application of thin Kirschner wires in Ilizarov apparatus is yet to be fully explained. To address this problem, load-deflection behavior of the pretensioned thin wires laterally loaded by the bone is necessary to be studied. In this paper, the lateral deflections of thin Kirschner wires are studied both theoretically and computationally. Fully three dimensional finite element (FE) modeling and analyses were performed in which the bone was modeled as a hollow cylinder, and the wire-bone interaction was assumed to be frictionless. The mathematical solution resulted in new exact solutions for the deflection as well as final tension in the wires subjected to the lateral loading under a cylinder representing the bone. Results from the FE analyses turned out to be very close to those from the mathematical solution. The results obtained from theory and FE method are comparable to published experimental findings. Some aspects of the pretensioned thin wire behavior in ring fixation systems, e.g., stiffness-tension proportionality, were revealed in the results. The current study adds to the existing knowledge on the general behavior of tensile elements.

Prediction of the yielding behaviour of ductile porous materials through computational homogenization

2018 ◽  
Vol 35 (2) ◽  
pp. 604-621
Author(s):  
Rodrigo Pinto Carvalho ◽  
Igor A. Rodrigues Lopes ◽  
Francisco M. Andrade Pires
Keyword(s):  
Three Dimensional ◽  
Yield Locus ◽  
Analytical Models ◽  
Finite Element Models ◽  
Content Type ◽  
Ductile Materials ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Void Geometry ◽  
The Impact

Purpose The purpose of this paper is to predict the yield locus of porous ductile materials, evaluate the impact of void geometry and compare the computational results with existing analytical models. Design/methodology/approach A computational homogenization strategy for the definition of the elasto-plastic transition is proposed. Representative volume elements (RVEs) containing single-centred ellipsoidal voids are analysed using three-dimensional finite element models under the geometrically non-linear hypothesis of finite strains. Yield curves are obtained by means of systematic analysis of RVEs considering different kinematical models: linear boundary displacements (upper bound), boundary displacement fluctuation periodicity and uniform boundary traction (lower bound). Findings The influence of void geometry is captured and the reduction in the material strength is observed. Analytical models usually overestimate the impact of void geometry on the yield locus. Originality/value This paper proposes an alternative criterion for porous ductile materials and assesses the accuracy of analytical models through the simulation of three-dimensional finite element models under geometrically non-linear hypothesis.

Force and Moment Characteristics of a Rhombi Tessellated Non-Pneumatic Tire

2016 ◽  
Vol 44 (2) ◽  
pp. 130-148 ◽  
Author(s):  
Anand Suresh Kumar ◽  
Ramarathnam Krishna Kumar
Keyword(s):  
Load Distribution ◽  
Three Dimensional ◽  
Element Model ◽  
Operating Conditions ◽  
Lateral Stiffness ◽  
Contact Pressure Distribution ◽  
Static Behavior ◽  
Pneumatic Tire ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

ABSTRACT There has been a recent spate of activities in the design of non-pneumatic tires (NPTs). The validation of a NPT's design is incomplete unless its performance is compared with an equivalent pneumatic tire. Apart from its static behavior, an evaluation of the tire's performance can be done by observing its force and moment (F&M) characteristics. In the present work, an NPT has been designed with an aperiodic rhombi tessellated spoke acting as the load bearing member, where the “unit cell” design is based on the vertical, circumferential, and lateral stiffness offered by the structure. A three-dimensional finite element model has been used to capture the mechanics of load distribution in the spoke, contact patch, and variation of contact pressure distribution when the tire is subjected to different operating conditions. SIMULIA/Abaqus has been used to conduct static loading, acceleration/braking, and cornering analyses. The F&M characteristics have been extracted from these simulations and compared with those of a 165/70R14 passenger car tire. The variation in the vertical and circumferential stiffness based on the spoke geometry has also been highlighted. The use of conventional pneumatic tire's belts to alter the NPT's lateral stiffness, despite the tire behaving like a “bottom loader,” adds uniqueness to the design. The NPT's capability to match the pneumatic tire's performance and the variability observed in the tire's F&M characteristics reiterate the freedom available in NPT design, thus providing the opportunity to have similar tires with varying performance characteristics.

Effective elastic moduli of metal honeycombs manufactured using selective laser melting

2020 ◽  
Vol 26 (5) ◽  
pp. 971-980 ◽  
Author(s):  
Rafid Hussein ◽  
Sudharshan Anandan ◽  
Myranda Spratt ◽  
Joseph W. Newkirk ◽  
K. Chandrashekhara ◽  
...  
Keyword(s):  
Strain Energy ◽  
Elastic Moduli ◽  
Three Dimensional ◽  
Analytical Models ◽  
Effective Elastic Moduli ◽  
Effective Moduli ◽  
Content Type ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Purpose Honeycomb cellular structures exhibit unique mechanical properties such as high specific strength, high specific stiffness, high energy absorption and good thermal and acoustic performance. This paper aims to use numerical modeling to investigate the effective elastic moduli, in-plane and out-of-plane, for thick-walled honeycombs manufactured using selective laser melting (SLM). Design/methodology/approach Theoretical predictions were performed using homogenization on a sample scale domain equivalent to the as-manufactured dimensions. A Renishaw AM 250 machine was used to manufacture hexagonal honeycomb samples with wall thicknesses of 0.2 to 0.5 mm and a cell size of 3.97 mm using 304 L steel powder. The SLM-manufactured honeycombs and cylindrical test coupons were tested using flatwise and edgewise compression. Three-dimensional finite element and strain energy homogenization were conducted to determine the effective elastic properties, which were validated by the current experimental outcomes and compared to analytical models from the literature. Findings Good agreement was found between the results of the effective Young’s moduli ratios numerical modeling and experimental observations. In-plane effective elastic moduli were found to be more sensitive to geometrical irregularity compared to out-of-plane effective moduli, which was confirmed by the analytical models. Also, it was concluded that thick-walled SLM manufactured honeycombs have bending-dominated in-plane compressive behavior and a stretch-dominated out-of-plane compressive behavior, which matched well with the simulation and numerical models predictions. Originality/value This work uses three-dimensional finite element and strain energy homogenization to evaluate the effective moduli of SLM manufactured honeycombs.

On the press fit of a crankpin into a circular web in pressed-up crankshafts

2003 ◽  
Vol 38 (3) ◽  
pp. 189-199 ◽  
Author(s):  
A Strozzi ◽  
P Vaccari
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Circumferential Stress ◽  
Three Dimensional ◽  
Analytical Models ◽  
Elastic Plane ◽  
Plane Model ◽  
Element Analysis ◽  
Press Fit ◽  
Three Dimensional Finite Element

The contact stresses induced by press-fitting a crankpin into a crankweb bore in pressed-up crankshafts are analysed for crankwebs possessing a circular geometry. The three-dimensional nature of this problem is reduced to a plane model, where the crankweb is described in terms of an eccentrically bored disc of uniform thickness, while the crankpin is idealized as an annular ring. Two different approaches are employed. Firstly, an elastic plane finite element analysis is carried out for this contact problem. Secondly, based upon the results of the numerical study, three variously approximated plane analytical models are developed. The contact pressure and the circumferential stress by the web bore are investigated, as well as the transmissible torque, where normalized diagrams are provided exploring a variety of disc-type crankweb geometries. Finally, selected three-dimensional finite element results are discussed, which highlight the limits of a plane model.

Assessment of Analytical Predictions for Radial Growth of Rotating Labyrinth Seals

2018 ◽  
Vol 35 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Sivakumar Subramanian ◽  
A. S. Sekhar ◽  
B. V. S. S. S. Prasad
Keyword(s):  
Rotational Speed ◽  
Radial Growth ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Analytical Models ◽  
Length Ratio ◽  
Labyrinth Seals ◽  
High Rotational Speed ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Abstract Radial growth predictions of rotating labyrinth seals are conventionally obtained from one-dimensional analytical models. However, these predictions quantitatively differ within themselves by about 5-500 %. Simulations using three-dimensional finite element method (FEM) are carried out in this paper for a typical labyrinth seal, subjected to high rotational speed and temperature, for a range of radius-to-length ratio of the rotor. Taking the predicted values by FEM as reference, four analytical models are assessed and their errors are quantified. These errors are found to be independent of rotational speed and temperature but significantly vary with the radius-to-length ratio of the rotor. Based on this finding, simple analytical models, together with correction factor charts, are suggested.

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