scholarly journals Characteristics, Optimal Design, and Performance Analyses of MRF Damper

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Xin De-kui ◽  
Nie Song-lin ◽  
Ji Hui ◽  
Yin Fang-long
Keyword(s):  
Shear Stress ◽  
Vibration Control ◽  
Mechanical Performance ◽  
Interpolation Method ◽  
Design Concept ◽  
Computational Method ◽  
Electromagnetic Properties ◽  
Damping Force ◽  
Element Analysis ◽  
Control Current

Magnetorheological fluid (MRF) damper is one of the most promising semiactive devices for vibration control. In this paper, a shear-valve mode MRF damper for pipeline vibration control is proposed. The dynamic model and the state equation of the pipeline are established and the linear quadratic regulator (LQR) is used to generate the optimal damping force of MRF damper. The design concept considering the structure and the electromagnetic properties simultaneously is discussed in detail. A mathematical model of the relation between shear stress and control current based on interpolation method is established. Finite element analysis (FEA) software COMSOL is selected to simulate the magnetic field and electromagnetism-thermal field of the MRF damper. A computational method based on the simulation model is established to calculate the shear stress. In order to reduce the magnetic leakage, a method of adding magnetism-insulators at both ends of the piston head is presented. The influence of control current, displacement, and velocity on mechanical performance of the proposed MRF damper is experimentally investigated. The test results show that the performance of the MRF damper is basically identical with the theoretical prospective and the simulation conclusions, which proves the correctness and feasibility of this design concept.

scholarly journals Multiphysics Analysis of a Magnetorheological Damper

2019 ◽  
Vol 69 (3) ◽  
pp. 230-235 ◽  
Author(s):  
A. J. D. Nanthakumar ◽  
J. Jancirani ◽  
S. C. Rajasekaran ◽  
K. Sarathkumar
Keyword(s):  
Shear Stress ◽  
Fluid Flow ◽  
Magnetic Flux ◽  
Vibration Control ◽  
Magnetorheological Damper ◽  
Flux Analysis ◽  
Fluid Viscosity ◽  
Damping Force ◽  
Magnetorheological Damping ◽  
Potential Tool

     A Magnetorheological damping has evolved as a potential tool in vibration control. The design of magnetorheological damping involves analysis of fluid flow principles and electromagnetic flux analysis. This research paper involves design and analysis of a magnetorheological damper employed for vibration control. The analysis is carried over by considering the domain as an axisymmetric model. The damping force of the damper depends upon the shear stress due to fluid viscosity and yield stress induced due to magnetic flux applied. The damping force generated by the damper is calculated.

scholarly journals Mechanical Performance and Design Method of Improved Lead Shear Damper with Long Stroke

2018 ◽  
Vol 2018 ◽  
pp. 1-18
Author(s):  
Baoshun Wang ◽  
Weiming Yan ◽  
Haoxiang He
Keyword(s):  
Mechanical Performance ◽  
Time History ◽  
Constitutive Law ◽  
Nonlinear Time History Analysis ◽  
Damping Force ◽  
Rigid Plastic ◽  
Element Analysis ◽  
High Rise ◽  
Long Period ◽  
Long Stroke

The paper presents experimental study on an improved plate lead shear damper with long stroke (ILSD-LS) which is developed to meet the engineering requirements for high-rise structures with long periods subjected to the long-period earthquakes. Finite element analysis is also carried out to investigate the proposed damper. Based on the ideal rigid-plastic constitutive law of lead, a mechanical model of the ILSD-LS is established. Compared with ordinary dampers, ILSD-LS has better damping force, energy dissipation capacity, and stability according to the results of simulation and experiments. The method of calculating damping force is reasonable and accurate. In order to verify the damping effect of ILSD-LS for the structures with long periods under long-period ground motions, the nonlinear time history analysis of a typical high-rise structure with ILSD-LS is carried out. The numerical results indicate that the seismic responses of the high-rise structure with ILSD-LS are significantly reduced when subjected to long-period ground motion.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

scholarly journals Design and Characterization of Microscale Auxetic and Anisotropic Structures Fabricated by Multiphoton Lithography

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 446
Author(s):  
Ioannis Spanos ◽  
Zacharias Vangelatos ◽  
Costas Grigoropoulos ◽  
Maria Farsari
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Performance ◽  
Element Analysis ◽  
Mechanical Responses ◽  
Multiphoton Lithography ◽  
Anisotropic Structures ◽  
Scanning Electron

The need for control of the elastic properties of architected materials has been accentuated due to the advances in modelling and characterization. Among the plethora of unconventional mechanical responses, controlled anisotropy and auxeticity have been promulgated as a new avenue in bioengineering applications. This paper aims to delineate the mechanical performance of characteristic auxetic and anisotropic designs fabricated by multiphoton lithography. Through finite element analysis the distinct responses of representative topologies are conveyed. In addition, nanoindentation experiments observed in-situ through scanning electron microscopy enable the validation of the modeling and the observation of the anisotropic or auxetic phenomena. Our results herald how these categories of architected materials can be investigated at the microscale.

scholarly journals Electromagnetic-Thermal Integration Design of Permanent Magnet Motor for Vehicles

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Shijun Chen ◽  
Qi Zhang ◽  
Surong Huang
Keyword(s):  
Permanent Magnet ◽  
High Performance ◽  
Design Method ◽  
Electromagnetic Properties ◽  
Permanent Magnet Motor ◽  
Element Analysis ◽  
Experiment Platform ◽  
Motor Design ◽  
Dimensional Parameters ◽  
Thermal Integration

To more efficiently design high performance vehicular permanent magnet motor, an electromagnetic-thermal integration design method is presented, which considers both the electromagnetic properties and the temperature rise of motor winding when determining the main dimensional parameters of the motor. Then a 48-slot and 8-pole vehicular permanent magnet motor is designed with this method. The thermomagnetic coupling design is simulated and validated on the basis of multiphysical domain on finite element analysis. Then the prototype is analyzed and tested on a newly built motor experiment platform. It is shown that the simulation results and experimental results are consistent, which validate the accuracy and effectiveness of the new design method. Also this method is proved to well improve the efficiency of permanent magnet motor design.

scholarly journals Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saurabhi Samant ◽  
Wei Wu ◽  
Shijia Zhao ◽  
Behram Khan ◽  
Mohammadali Sharzehee ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Patient Specific ◽  
Wall Structure ◽  
Left Main ◽  
Element Analysis ◽  
Stent Expansion ◽  
Radial Strength ◽  
Different Diameters

AbstractLeft main (LM) coronary artery bifurcation stenting is a challenging topic due to the distinct anatomy and wall structure of LM. In this work, we investigated computationally and experimentally the mechanical performance of a novel everolimus-eluting stent (SYNERGY MEGATRON) purpose-built for interventions to large proximal coronary segments, including LM. MEGATRON stent has been purposefully designed to sustain its structural integrity at higher expansion diameters and to provide optimal lumen coverage. Four patient-specific LM geometries were 3D reconstructed and stented computationally with finite element analysis in a well-validated computational stent simulation platform under different homogeneous and heterogeneous plaque conditions. Four different everolimus-eluting stent designs (9-peak prototype MEGATRON, 10-peak prototype MEGATRON, 12-peak MEGATRON, and SYNERGY) were deployed computationally in all bifurcation geometries at three different diameters (i.e., 3.5, 4.5, and 5.0 mm). The stent designs were also expanded experimentally from 3.5 to 5.0 mm (blind analysis). Stent morphometric and biomechanical indices were calculated in the computational and experimental studies. In the computational studies the 12-peak MEGATRON exhibited significantly greater expansion, better scaffolding, smaller vessel prolapse, and greater radial strength (expressed as normalized hoop force) than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY (p < 0.05). Larger stent expansion diameters had significantly better radial strength and worse scaffolding than smaller stent diameters (p < 0.001). Computational stenting showed comparable scaffolding and radial strength with experimental stenting. 12-peak MEGATRON exhibited better mechanical performance than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY. Patient-specific computational LM stenting simulations can accurately reproduce experimental stent testing, providing an attractive framework for cost- and time-effective stent research and development.

Frequency Shaped Semi-Active Control for Magnetorheological Fluid-Based Vibration Control Systems

2013 ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley ◽  
Gregory J. Hiemenz
Keyword(s):  
Vibration Control ◽  
Control Systems ◽  
Active Control ◽  
Control Algorithm ◽  
Active Vibration Control ◽  
Control Algorithms ◽  
Model Parameters ◽  
Mr Fluid ◽  
Control Current ◽  
Active Vibration

Novel semi-active vibration controllers are developed in this study for magnetorheological (MR) fluid-based vibration control systems, including: (1) a band-pass frequency shaped semi-active control algorithm, (2) a narrow-band frequency shaped semi-active control algorithm. These semi-active vibration control algorithms designed without resorting to the implementation of an active vibration control algorithms upon which is superposed the energy dissipation constraint. These new Frequency Shaped Semi-active Control (FSSC) algorithms require neither an accurate damper (or actuator) model, nor system identification of damper model parameters for determining control current input. In the design procedure for the FSSC algorithms, the semi-active MR damper is not treated as an active force producing actuator, but rather is treated in the design process as a semi-active dissipative device. The control signal from the FSSC algorithms is a control current, and not a control force as is typically done for active controllers. In this study, two FSSC algorithms are formulated and performance of each is assessed via simulation. Performance of the FSSC vibration controllers is evaluated using a single-degree-of-freedom (DOF) MR fluid-based engine mount system. To better understand the control characteristics and advantages of the two FSSC algorithms, the vibration mitigation performance of a semi-active skyhook control algorithm, which is the classical semi-active controller used in base excitation problems, is compared to the two FSSC algorithms.

scholarly journals Computational biomechanical analyses demonstrate similar shell-crushing abilities in modern and ancient arthropods

2018 ◽  
Vol 285 (1889) ◽  
pp. 20181935 ◽  
Author(s):  
Russell D. C. Bicknell ◽  
Justin A. Ledogar ◽  
Stephen Wroe ◽  
Benjamin C. Gutzler ◽  
Winsor H. Watson ◽  
...  
Keyword(s):  
Horseshoe Crab ◽  
Dietary Habits ◽  
Mechanical Performance ◽  
Limulus Polyphemus ◽  
Gut Contents ◽  
Computational Techniques ◽  
Element Analysis ◽  
Animal Evolution ◽  
Fossil Species ◽  
Feeding Mechanics

The biology of the American horseshoe crab, Limulus polyphemus , is well documented—including its dietary habits, particularly the ability to crush shell with gnathobasic walking appendages—but virtually nothing is known about the feeding biomechanics of this iconic arthropod. Limulus polyphemus is also considered the archetypal functional analogue of various extinct groups with serial gnathobasic appendages, including eurypterids, trilobites and other early arthropods, especially Sidneyia inexpectans from the mid-Cambrian (508 Myr) Burgess Shale of Canada. Exceptionally preserved specimens of S. inexpectans show evidence suggestive of durophagous (shell-crushing) tendencies—including thick gnathobasic spine cuticle and shelly gut contents—but the masticatory capabilities of this fossil species have yet to be compared with modern durophagous arthropods. Here, we use advanced computational techniques, specifically a unique application of 3D finite-element analysis (FEA), to model the feeding mechanics of L. polyphemus and S. inexpectans : the first such analyses of a modern horseshoe crab and a fossil arthropod. Results show that mechanical performance of the feeding appendages in both arthropods is remarkably similar, suggesting that S. inexpectans had similar shell-crushing capabilities to L. polyphemus . This biomechanical solution to processing shelly food therefore has a history extending over 500 Myr, arising soon after the first shell-bearing animals. Arrival of durophagous predators during the early phase of animal evolution undoubtedly fuelled the Cambrian ‘arms race’ that involved a rapid increase in diversity, disparity and abundance of biomineralized prey species.

scholarly journals Mechanical Properties of a Biocomposite Based on Carbon Nanotube and Graphene Nanoplatelet Reinforced Polymers: Analytical and Numerical Study

2021 ◽  
Vol 5 (9) ◽  
pp. 234
Author(s):  
Marwane Rouway ◽  
Mourad Nachtane ◽  
Mostapha Tarfaoui ◽  
Nabil Chakhchaoui ◽  
Lhaj El Hachemi Omari ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Numerical Study ◽  
Turbine Blades ◽  
Natural Fibers ◽  
Computational Method ◽  
Wind Turbine Blades ◽  
Reinforced Polymer ◽  
Analytical Approaches

Biocomposites based on thermoplastic polymers and natural fibers have recently been used in wind turbine blades, to replace non-biodegradable materials. In addition, carbon nanofillers, including carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are being implemented to enhance the mechanical performance of composites. In this work, the Mori–Tanaka approach is used for homogenization of a polymer matrix reinforced by CNT and GNP nanofillers for the first homogenization, and then, for the second homogenization, the effective matrix was used with alfa and E-glass isotropic fibers. The objective is to study the influence of the volume fraction Vf and aspect ratio AR of nanofillers on the elastic properties of the composite. The inclusions are considered in a unidirectional and random orientation by using a computational method by Digimat-MF/FE and analytical approaches by Chamis, Hashin–Rosen and Halpin–Tsai. The results show that CNT- and GNP-reinforced nanocomposites have better performance than those without reinforcement. Additionally, by increasing the volume fraction and aspect ratio of nanofillers, Young’s modulus E increases and Poisson’s ratio ν decreases. In addition, the composites have enhanced mechanical characteristics in the longitudinal orientation for CNT- reinforced polymer and in the transversal orientation for GNP-reinforced polymer.

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