Force-Deflection Characteristics of SMA-Based Belleville Springs

2012 ◽  
Author(s):  
Franco Furgiuele ◽  
Carmine Maletta ◽  
Emanuele Sgambitterra
Keyword(s):  
Numerical Simulations ◽  
Mechanical Response ◽  
Nickel Titanium ◽  
Thermally Induced ◽  
Niti Alloys ◽  
Strain Behavior ◽  
Finite Element Software ◽  
Transition Mechanism ◽  
Functional Features ◽  
Software Code

The thermo-mechanical properties of Nickel-Titanium based Belleville washers have been analyzed by numerical simulations. In fact, these components exhibit unique mechanical and functional features due to the reversible stress-induced and/or thermally-induced phase transition mechanism of NiTi alloys. The numerical simulations have been carried out by using a commercial finite element software code and a special constitutive model for SMAs. The effects of the geometrical configuration of the washers as well as of the operating temperature, under fully austenitic conditions, have been analyzed. The results highlighted a marked hysteretic response, in terms of force-deflection curve, due to the hysteresis in the stress-strain behavior of NiTi alloys. In addition, a marked influence of the geometry, as well as of the temperature, has been observed on the thermo-mechanical response of the washer, i.e. in terms of both mechanical and functional properties.

NiTi Belleville washers: Design, manufacturing and testing

2012 ◽  
Vol 24 (6) ◽  
pp. 695-703 ◽  
Author(s):  
Carmine Maletta ◽  
Luigino Filice ◽  
Franco Furgiuele
Keyword(s):  
Characteristic Curve ◽  
Thermomechanical Properties ◽  
Nickel Titanium ◽  
Hysteretic Behavior ◽  
Thermal Cycles ◽  
Finite Element Software ◽  
Phase Transition Temperatures ◽  
Transformation Mechanisms ◽  
Functional Features ◽  
Stiffness And Damping

The thermomechanical properties of nickel–titanium-based Belleville washers have been analyzed in this investigation, together with their unusual mechanical and functional features, which can be attributed to the reversible phase transformation mechanisms of nickel–titanium alloys. In particular, numerical simulations have been carried out for a preliminary design of the Belleville washer, using a commercial finite element software and a special constitutive model for shape memory alloys. Subsequently, Belleville washers have been manufactured from a commercial pseudoelastic nickel–titanium alloy, by disk cutting and a successive shape setting by a thermomechanical treatment. Finally, the thermomechanical response of the washers, in terms of isothermal force–deflection curve and thermal cycles between phase transition temperatures, has been experimentally analyzed. The results highlighted a marked effect of the temperature on the characteristic curve, as well as good recovery capabilities under both mechanical and thermal cycles. In addition, nickel–titanium Belleville washers exhibit a marked hysteretic behavior, as a consequence of the hysteresis in the stress–strain response of the alloy. Thanks to these features, nickel–titanium Belleville washers can be used as smart elastic elements, that is, with tunable stiffness and damping properties, as well as solid-state actuators, due to their recovery capabilities.

scholarly journals A numerical investigation on impulse-induced nonlinear longitudinal waves in pantographic beams

2021 ◽  
pp. 108128652110108
Author(s):  
Emilio Turco ◽  
Emilio Barchiesi ◽  
Francesco dell’Isola
Keyword(s):  
Numerical Simulations ◽  
Mechanical Response ◽  
Integration Scheme ◽  
Present Contribution ◽  
Longitudinal Waves ◽  
Deformation Regime ◽  
Impulsive Loads ◽  
Unit Cells ◽  
Statics And Dynamics ◽  
Equations Of Motions

This contribution presents the results of a campaign of numerical simulations aimed at better understanding the propagation of longitudinal waves in pantographic beams within the large-deformation regime. Initially, we recall the key features of a Lagrangian discrete spring model, which was introduced in previous works and that was tested extensively as capable of accurately forecasting the mechanical response of structures based on the pantographic motif, both in statics and dynamics. Successively, a stepwise integration scheme used to solve equations of motions is briefly discussed. The key content of the present contribution concerns the thorough presentation of some selected numerical simulations, which focus in particular on the propagation of stretch profiles induced by impulsive loads. The study takes into account different tests, by varying the number of unit cells, i.e., the total length of the system, spring stiffnesses, the shape of the impulse, as well as its properties such as duration and peak amplitude, and boundary conditions. Some conjectures about the form of traveling waves are formulated, to be confirmed by both further numerical simulations and analytical investigations.

Mechanical Response of Different Lattice Structures Fabricated Using the CLIP Technology

2016 ◽  
Author(s):  
Anil Saigal ◽  
John R. Tumbleston ◽  
Hendric Vogel
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Response ◽  
Elastic Response ◽  
Lattice Structures ◽  
Rhombic Dodecahedron ◽  
Structured Materials ◽  
Specific Strength ◽  
Strain Behavior ◽  
End Use ◽  
Continuous Liquid Interface Production

In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, ultralight, ultrastiff end-use parts. This research investigates the mechanical behavior of octahedral, octet, vertex centroid, dode, diamond, rhombi octahedron, rhombic dodecahedron and solid lattice structured polyacrylate fabricated using Continuous Liquid Interface Production (CLIP) technology based on 3D printing and additive manufacturing processes. The compressive stress-strain behavior of the lattice structures observed is typical of cellular structures which include a region of nominally elastic response, yielding, plastic strain hardening to a peak in strength, followed by a drop in flow stress to a plateau region and finally rapid hardening associated with contact of the deformed struts with each other as part of densification. It was found that the elastic modulus and strength of the various lattice structured materials are proportional to each other. In addition, it was found that the octahedral, octet and diamond lattice structures are amongst the most efficient based on the measured specific stiffness and specific strength.

Continuum Description of the Time- and Strain-Dependent Poisson’s Ratio of Ligament Under Finite Deformation

2013 ◽  
Author(s):  
Aaron M. Swedberg ◽  
Shawn P. Reese ◽  
Steve A. Maas ◽  
Benjamin J. Ellis ◽  
Jeffrey A. Weiss
Keyword(s):  
Large Scale ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Large Strain ◽  
Fiber Direction ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Poisson's Ratios ◽  
Poisson’S Ratios ◽  
Strain Dependent

Ligament volumetric behavior controls fluid and thus nutrient movement as well as the mechanical response of the tissue to applied loads. The reported Poisson’s ratios for tendon and ligament subjected to tensile deformation loading along the fiber direction are large, ranging from 0.8 ± 0.3 in rat tail tendon fascicles [1] to 2.98 ± 2.59 in bovine flexor tendon [2]. These Poisson’s ratios are indicative of volume loss and thus fluid exudation [3,4]. We have developed micromechanical finite element models that can reproduce both the characteristic nonlinear stress-strain behavior and large, strain-dependent Poisson’s ratios seen in tendons and ligaments [5], but these models are computationally expensive and unfeasible for large scale, whole joint models. The objectives of this research were to develop an anisotropic, continuum based constitutive model for ligaments and tendons that can describe strain-dependent Poisson’s ratios much larger than the isotropic limit of 0.5. Further, we sought to demonstrate the ability of the model to describe experimental data, and to show that the model can be combined with biphasic theory to describe the rate- and time-dependent behavior of ligament and tendon.

Research on Thermally Induced Deformation of Reinforcing Plate Based on Finite Element Simulation

2012 ◽  
Vol 197 ◽  
pp. 139-143
Author(s):  
Hua Bai ◽  
Yi Du Zhang
Keyword(s):  
Finite Element ◽  
Ambient Temperature ◽  
Finite Element Simulation ◽  
Temperature Change ◽  
Large Scale ◽  
Machining Process ◽  
Reinforcement Structure ◽  
Thermally Induced ◽  
Finite Element Software ◽  
Element Simulation

The change of ambient temperature will cause deformation during the machining process of large-scale aerospace monolithic component. Based on finite element simulation, thermally induced deformation of reinforcing plate is studied in such aspects as reinforcement structure, clamping method and temperature change, and contact function in finite element software is used to simulate the unilateral constraint between workpiece and worktable. The results indicate that reinforcing plate will produce warping deformation due to the change of ambient temperature. Different reinforcement structures and clamping methods have important influence on the deformation positions and degrees, and the deformation is proportional to the temperature change.

scholarly journals Enhancing Mechanical Response of Monolithic Magnesium Using Nano-NiTi (Nitinol) Particles

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1014 ◽  
Author(s):  
Gururaj Parande ◽  
Vyasaraj Manakari ◽  
Saif Wakeel ◽  
Milli Kujur ◽  
Manoj Gupta
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Hot Extrusion ◽  
Nickel Titanium ◽  
Structure Property ◽  
Microstructural Characteristics ◽  
Magnesium Matrix ◽  
Melt Deposition ◽  
Synthesized Materials ◽  
Minimal Adverse Effect

The present study focuses on investigating the effects of Nickel-Titanium (NiTi) nanoparticles on the microstructure and properties of pure Mg. Mg composites containing varying weight percentages (0.5, 1, 1.5, 3) of NiTi nanoparticles were fabricated using Disintegrated Melt Deposition (DMD), followed by hot extrusion. The synthesized materials were characterized in order to investigate their physical, microstructural and mechanical properties. Synthesized materials were characterized for their density and porosity levels, microstructural characteristics, and mechanical response. Superior grain refinement was realized by the presence of NiTi nanoparticles in the magnesium matrix. The addition of NiTi nanoparticles resulted in strength property enhancements of pure Mg with minimal adverse effect on the ductility. Structure-property evaluations are detailed in the current study.

scholarly journals Simulation of Cyclic Loading on Pipe Elbows Using Advanced Plane-Stress Elastoplasticity Models1

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Konstantinos Chatziioannou ◽  
Yuner Huang ◽  
Spyros A. Karamanos
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Mechanical Response ◽  
Low Cycle Fatigue ◽  
Constitutive Relations ◽  
Cyclic Plasticity ◽  
Integration Scheme ◽  
Repeated Loading ◽  
Finite Element Software ◽  
Hardening Models

Abstract This work investigates the response of industrial steel pipe elbows subjected to severe cyclic loading (e.g., seismic or shutdown/startup conditions), associated with the development of significant inelastic strain amplitudes of alternate sign, which may lead to low-cycle fatigue. To model this response, three cyclic-plasticity hardening models are employed for the numerical analysis of large-scale experiments on elbows reported elsewhere. The constitutive relations of the material model follow the context of von Mises cyclic elasto-plasticity, and the hardening models are implemented in a user subroutine, developed by the authors, which employs a robust numerical integration scheme, and is inserted in a general-purpose finite element software. The three hardening models are evaluated in terms of their ability to predict the strain range at critical locations, and in particular, strain accumulation over the load cycles, a phenomenon called “ratcheting.” The overall good comparison between numerical and experimental results demonstrates that the proposed numerical methodology can be used for simulating accurately the mechanical response of pipe elbows under severe inelastic repeated loading. Finally, this paper highlights some limitations of conventional hardening rules in simulating multi-axial material ratcheting.

scholarly journals Sub-impacts of simply supported beam struck by steel sphere—part II: Numerical simulations

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668335
Author(s):  
Xiaoli Qi ◽  
Xiaochun Yin
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Great Influence ◽  
Element Model ◽  
Theoretical Expression ◽  
Curvature Radius ◽  
Steel Sphere ◽  
Impact Time ◽  
Finite Element Software ◽  
Contact Impact

This part of the article describes numerical simulations of the problem investigated experimentally. A three-dimensional finite element model of elastic–plastic for sphere falling on beam has been implemented using the nonlinear dynamic finite element software LS-DYNA. From the numerical simulations, it was found that the LS-DYNA is suitable to study complex sub-impact phenomenon, and good agreement is in general obtained between the simulation and experimental results. The numerical simulations show that the initial impact velocity, equivalent elasticity modulus, contact curvature radius of the sphere, and equivalent mass have great influence on the contact–impact time of the sub-impact, and an applicable range of the theoretical expression of contact–impact time of the sub-impact was determined. In addition, the numerical simulations demonstrate the ratios of maximum amplitudes of the first-, second-, and third-order vibrations to the maximum amplitudes of the beam vibrations, and the phase angle of the first-order vibration will change suddenly when the sub-impacts occur. Furthermore, the occurrence conditions of the sub-impacts were clarified numerically. It was found that the occurrence conditions of the sub-impacts can be represented by a mass ratio threshold, and the thickness or length of the beam has also a great influence on the occurrence of the sub-impacts. Once the sub-impacts occur, which would result in an uncertain behavior of the apparent coefficient of restitution.

scholarly journals Influence of Thermomechanical Treatment on the Mechanical Behavior of Protaper Gold versus Protaper Universal (A Finite Element Study)

2019 ◽  
Vol 7 (13) ◽  
pp. 2157-2161 ◽  
Author(s):  
Manar Galal ◽  
Amira Galal Ismail ◽  
Nada Omar ◽  
Mohamed Zaazou ◽  
Mohamed Abdallah Nassar
Keyword(s):  
Finite Element ◽  
Thermomechanical Treatment ◽  
Mechanical Response ◽  
3D Models ◽  
Nickel Titanium ◽  
Element Analysis ◽  
Torsional Resistance ◽  
Cad Cam ◽  
Flexural Resistance ◽  
Cam Software

AIM: To compare and evaluate the influence of thermomechanical treatment of Protaper Gold file versus Protaper Universal file during testing of bending and torsion using finite-element analysis. METHODS: Two nickel-titanium NiTi rotary files (ProTaper Gold and ProTaper Universal) were used in this study. The files were imaged using stereomicroscope to produce 3D models. The behaviour of the instrument during bending and torsion was numerically analysed in CAD/CAM software package. RESULTS: Under bending, ProTaper, Gold showed higher flexibility and flexural resistance than ProTaper Universal. The highest stress was related at the cutting edge of both files. While during testing of torsion, the maximum amount of stresses was related to the base of the flutes in both files. ProTaper Gold showed higher torsional resistance than the ProTaper Universal file. CONCLUSION: Thermomechanical treatment improved the mechanical response (bending and torsional resistance) of NiTi files.

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