An Isoparametric Four-Node Beam Element for the Analysis of Planar Robot Manipulators

1993 ◽  
Author(s):  
Ahmad A. Smaili ◽  
Muhammad Sannah
Keyword(s):  
High Speed ◽  
Structural Characteristics ◽  
Accurate Determination ◽  
Element Model ◽  
Beam Element ◽  
Body Motion ◽  
Nonlinear Transient ◽  
Rigid Joints ◽  
Derivatives Of

Abstract Accurate determination of the dynamic response of high speed flexible manipulators requires that the dynamic model incorporates the influence of joint compliances, in addition to faithfully representing the physical characteristics of the links. A finite element model is herein presented for this purpose. The model is based on a 4-node isoparametric Timoshenko beam element to model the structural characteristics of the links including the effects of shear deformation and rotary inertia. It also includes the influence of the rigid body motion and the time derivatives of the elastic deformations of the manipulator on the characteristic matrices of the system, and accounts for the inertia of the drive units and payload and the damping of externally applied dampers. Quasistatic analysis, modal analysis, and linear and nonlinear vibrational responses of a 3-R planar manipulator are determined by solving the appropriate equations of equilibrium. The results of the analysis revealed that the compliance of the joints have a considerable influence on the manipulator response which is manifested by considerable increase in endpoint deflections and substantial decrease in fundamental natural frequency. Nonlinear transient response exhibited a behavior that differs drastically from that obtained when rigid joints are assumed.

Harmonic Analysis of the High-Speed Winder with Unbalance Masses

2013 ◽  
Vol 300-301 ◽  
pp. 974-977
Author(s):  
Xi Hou ◽  
Hui Zhang ◽  
Sheng Ze Wang
Keyword(s):  
High Speed ◽  
Dynamic Balance ◽  
Element Model ◽  
Beam Element ◽  
Response Analysis ◽  
Rotatory Inertia ◽  
Harmonic Response ◽  
Finite Element Software ◽  
Calculation Results ◽  
Harmonic Response Analysis

A finite beam element model of the spindle which is one of key parts of the high-speed winder is presented in this paper. Critical speeds of the spindle based on the finite beam element model are obtained considering the effect of rotatory inertia, gyroscopic moments, and the damping. Harmonic response analysis of the high-speed winder spindle is developed in two conditions including static unbalance and couple unbalance. The dynamic analysis mentioned above is implemented by using the finite element software ANSYS. Calculation results in this paper are helpful for the dynamic balance of the high-speed winder spindle.

Factors affecting the accurate determination of cerebrovascular blood flow using high-speed droplet imaging

1998 ◽  
Author(s):  
Stephen Rudin ◽  
Afshin Divani ◽  
Ajay K. Wakhloo ◽  
Baruch B. Lieber ◽  
William Granger ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Accurate Determination ◽  
Factors Affecting

Finite Element Analysis of Beams With Constrained Damping Treatment Modeled Via Fractional Derivatives

1997 ◽  
Vol 50 (11S) ◽  
pp. S216-S224 ◽  
Author(s):  
Luis E. Sua´rez ◽  
Arsalan Shokooh ◽  
Jose´ Arroyo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Single Layer ◽  
Element Model ◽  
Beam Element ◽  
Element Formulation ◽  
Beam Model ◽  
Element Analysis ◽  
Damping Material ◽  
Derivatives Of

This paper presents a finite element formulation for the modeling of beams and frames with artificial damping provided by means of a constrained single layer of damping material. The behavior of the damping material is described using the fractional derivative model of viscoelasticity. In this model, the first order derivatives of the strains in the constitutive equations of the viscoelastic materials are replaced by derivatives of order α < 1. The finite element model developed is a one-dimensional beam element with three degrees of freedom per node. The dynamic response is calculated with a procedure involving a transformation of the original equations of motion to the state space and its decoupling with the eigenvectors of a special eigenvalue problem. The accuracy of the modal properties obtained with the beam model is compared with those calculated from a more elaborate plane stress finite element model. It was found that the proposed beam element provides very accurate results and with much lower computational costs than the 2-D model.

Accurate Determination of the Cold Detection Threshold with High-Speed Cooling of the Skin

Pain Medicine ◽  
2020 ◽  
Vol 21 (12) ◽  
pp. 3428-3436
Author(s):  
Segolene Lithfous ◽  
Olivier Després ◽  
Thierry Pebayle ◽  
Claudia Casadio ◽  
Andre Dufour
Keyword(s):  
High Speed ◽  
Accurate Determination ◽  
Detection Threshold ◽  
Detection Thresholds ◽  
Temperature Ramp ◽  
Temperature Ramps ◽  
The Subject ◽  
Order Four ◽  
Healthy Participants

Abstract Objective This study used high-speed cooling of the skin and exact control of stimulus duration to measure the cold detection threshold in healthy participants. The objective was to compare the method of limits, in which the temperature is slowly and gradually increased/decreased until the subject perceives the stimulation, and the method of levels, in which the subject must detect brief thermal stimulations close to the threshold of perception. Methods Twenty healthy volunteers (nine women, 11 men) aged 20–30 years participated in the study. The method of limits and method of levels were performed in all subjects in a counterbalanced order. Four cold detection thresholds were measured with the method of levels, with a temperature ramp of 300°C/sec and stimulus durations of 50 ms, 100 ms, 300 ms, and 500 ms. Three thresholds were measured with the method of limits, with temperature ramps of 1°C/sec, 2°C/sec, and 4°C/sec. Results On average, the cold detection thresholds were −0.47°C below skin temperature with the method of levels and −1.67°C the method of limits. Interindividual variability was significantly lower with the method of levels than with the method of limits. Conclusions These results suggest that the method of levels is more accurate than the method of limits for measuring cold detection threshold. The improvement of cold detection threshold measurement may provide new perspectives to more precisely assess the function of A-delta fibers and the spino-thalamic pathway.

scholarly journals New high-speed centre of mass method incorporating background subtraction for accurate determination of fluorescence lifetime

2016 ◽  
Vol 24 (7) ◽  
pp. 6899 ◽  
Author(s):  
Simon P. Poland ◽  
Ahmet T. Erdogan ◽  
Nikola Krstajić ◽  
James Levitt ◽  
Viviane Devauges ◽  
...  
Keyword(s):  
Fluorescence Lifetime ◽  
Background Subtraction ◽  
High Speed ◽  
Accurate Determination ◽  
Centre Of Mass

Experimental device for the accurate determination of wood-water relations on micro-samples

Holzforschung ◽  
2007 ◽  
Vol 61 (4) ◽  
pp. 419-429 ◽  
Author(s):  
Patrick Perré
Keyword(s):  
Moisture Content ◽  
Water Relations ◽  
High Speed ◽  
Growth Ring ◽  
Accurate Determination ◽  
Longitudinal Direction ◽  
Experimental Device ◽  
Normal Wood ◽  
Diamond Wire Saw

Abstract This paper describes an experimental device designed for the accurate determination of wood/water relations on micro-samples. The moisture content of the sample is measured with a highly sensitive electronic microbalance. Moreover, the dimensions of the sample in tangential and longitudinal direction are collected continuously without contact by means of two high-speed laser scan micrometers. The device is placed in a climatic chamber. The micro-samples investigated were prepared with a diamond wire saw. A sample thickness of less than 1 mm allows the moisture content to be almost uniform during the test. The data obtained are of excellent quality and accuracy, in spite of the very small mass and dimensions of the samples. The device provides a perfect tool for investigating the dynamic interaction between relative humidity, moisture content, and shrinkage. Results collected for beech, spruce and eucalyptus are presented. Important findings include: deviation from a linear relation between shrinkage and moisture content in beech; uniqueness of the shrinkage versus moisture content curve during desorption/adsorption cycles; evidence of cell collapse in eucalyptus, especially for tension wood; and property variations within the growth ring of normal wood and compression wood of spruce.

scholarly journals Determination of digesta flow entering the omasal canal of dairy cows using different marker systems

2003 ◽  
Vol 90 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Seppo Ahvenjärvi ◽  
Aila Vanhatalo ◽  
Kevin J. Shingfield ◽  
Pekka Huhtanen
Keyword(s):  
Particulate Matter ◽  
Liquid Phase ◽  
Dairy Cows ◽  
High Speed ◽  
Volatile Fatty Acids ◽  
Accurate Determination ◽  
Water Soluble ◽  
Neutral Detergent Fibre ◽  
Inorganic Matter

Four studies were conducted to compare the effect of four indigestible markers (LiCoEDTA, Yb-acetate, Cr-mordanted straw and indigestible neutral-detergent fibre (INDF)) and three marker systems on the flow of digesta entering the omasal canal of lactating dairy cows. Samples of digesta aspirated from the omasal canal were pooled and separated using filtration and high-speed centrifugation into three fractions defined as the liquid phase, small particulate and large particulate matter. Co was primarily associated with the liquid phase, Yb was concentrated in small particulate matter, whilst Cr and INDF were associated with large particles. Digesta flow was calculated based on single markers or using the reconstitution system based on combinations of two (Co + Yb, Co + Cr and Co + INDF) or three markers (Co + Yb + Cr and Co + Yb + INDF). Use of single markers resulted in large differences between estimates of organic matter (OM) flow entering the omasal canal suggesting that samples were not representative of true digesta. Digesta appeared to consist of at least three phases that tended to separate during sampling. OM was concentrated in particulate matter, whilst the liquid phase consisted mainly of volatile fatty acids and inorganic matter. Yb was intimately associated with nitrogenous compounds, whereas Cr and INDF were concentrated in fibrous material. Current data indicated that marker systems based on Yb in combination with Cr or INDF are required for the accurate determination of OM, N and neutral-detergent fibre flow. In cases where the flow of water-soluble nutrients entering the omasal canal is also required, the marker system should also include Co.

High-Speed Wave-Piercing Catamaran Global Loads Determined by FEA and Sea Trials

2019 ◽  
Vol 161 (A2) ◽  
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Local Strain ◽  
Element Model ◽  
Sensor Data ◽  
Design Stage ◽  
High Speeds ◽  
Design Loads ◽  
Hull Forms

Wave-piercing catamaran hull forms are widely used for high-speed ferry applications due to the hull slenderness, suitable for achieving high speeds. The global loads acting on these craft are of great interest as there is limited knowledge on determining the magnitude of the loads, in particular when operating in random sea conditions. Longitudinal and transverse bending moments as well as pitch connecting moments and hull torsion loads act on the hull simultaneously. This paper investigates the estimation of these global loads from full-scale catamaran sea trials strain gauge data using finite element methods. Det Norske Veritas (DNV) load cases are applied to a finite element model in order to determine the conversion between local strain values observed during sea trials and prevailing global loads. Comparisons are thus made of global loads determined from strain data collected from sea trials with DNV global load cases. The results show that this method is relatively reliable for the prediction of hull global loads in the absence of slamming. Comparisons have been made for different heading angles. The quasi-static design loads are important during the ship design stage, as they are good proxies in wavelengths comparable to the hull length for rationally determined loads obtained from a first-principles dynamic analysis. The broad aims here are to demonstrate the use of strain sensor data obtained during sea trials for determination of global sea loads, to reconcile the loads thus determined with DNV load cases and thereby to improve the accuracy of the predicted loads used in design to increase the structural efficiency of vessel design.

Study on Deflection Performance of Radial Tire by Finite Element Method

2011 ◽  
Vol 42 (11) ◽  
pp. 30-35
Author(s):  
Gang Cheng ◽  
Guoqun Zhao ◽  
Yanjin Guan ◽  
Zhonglei Wang
Keyword(s):  
Finite Element ◽  
Nonlinear Boundary ◽  
Accurate Determination ◽  
Element Model ◽  
Nonlinear Boundary Conditions ◽  
Contact Friction ◽  
Radial Tire ◽  
The Road ◽  
Contact Stress Distribution

In order to improve vehicle safety, the accurate determination of the tire's loading behaviour is necessary in the domain of vehicle dynamics. The interaction between the tire and the surface of the road must be understood thoroughly. A 3D finite element model of the tire-road has been built by using MARC software according to the actual construction of the 195/60R14 radial tire. The rebar model of the radial tire is employed to simulate the complex multilayer cord-rubber composites and directly define the cord directions varying with their positions. The geometric nonlinearity due to large deformation, material nonlinearity and the nonlinear boundary conditions from tire–rim contact and tire–road contact are also considered. The relationships between load and the tire deflection, the tire deformation, the contact stress distribution and the distribution of the contact friction force are discussed.

Vibration Forecast and Vibration Attenuation Research of the Finished Motorcycle Based on Virtual Analysis

2014 ◽  
Vol 705 ◽  
pp. 122-125
Author(s):  
Zi Qing Meng ◽  
Ming Li
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
High Speed ◽  
Structural Characteristics ◽  
Element Model ◽  
Analysis Model ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Vibration Attenuation ◽  
Response Equation

as the high-speed vehicle, motorcycle vibration has an important influence on driving security, comfort, and handling stability. Therefore, this article builds the finite element analysis model of vibration forecast and damping of the finished motorcycle based on the structural characteristics. The major contents include main part modeling, boundary condition, and the finite element model of the finished motorcycle. In the paper, we build the finite dynamic response equation through analyzing the dynamic response, and research the resonance from different directions that caused by the engine harmonic response. Moreover, this article provides the vibration attenuation plan of the motorcycle structural modification and proves the feasibility through the analog computation and experimental measurement.

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