Determination of Dynamic Characteristics of an Impact Forming Machine Structure

1978 ◽  
Vol 100 (4) ◽  
pp. 434-440 ◽  
Author(s):  
A. E. M. Osman ◽  
W. A. Knight ◽  
M. M. Sadek
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Dynamic Testing ◽  
Accurate Determination ◽  
Noise Levels ◽  
Structural Vibrations ◽  
Modes Of Vibration ◽  
High Speed Forming ◽  
Machine Structure

The noise generated from an impact forming machine arises mainly from structural vibrations and consequently accurate determination of the modal characteristics of the machine is necessary in order to bring about design modifications with the aim of reducing noise levels. Various methods of dynamic testing are applied to a high speed forming machine structure. It is found that the modes of vibration can be successfully identified by impulse tests, with the force pulse generated either by operation of the machine or by means of a hand held hammer.

Determination of Dynamic Characteristics of Welded Joints Made of Steel S460NL

2014 ◽  
Vol 224 ◽  
pp. 267-275 ◽  
Author(s):  
Wiesław Barnat ◽  
Marek Kordys
Keyword(s):  
Plastic Deformation ◽  
Dynamic Characteristics ◽  
Welded Joints ◽  
High Speed ◽  
Steel Structures ◽  
Basic Material ◽  
Engineering Structures ◽  
Static Tests ◽  
Very High

Examination of the behavior of materials under very high speed plastic deformation are widely used during the designing process of dynamically loaded steel structures. Steel is widely used as a basic material for designing engineering structures. Characteristics of steel obtained under static experiments are different from those obtained during static tests.

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

Optimized Design and Performance Study of High Speed Five-Axis Machine Tools

2020 ◽  
Author(s):  
Tzu-Chi Chan ◽  
Jyun-Sian Yang
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
High Speed ◽  
Spectral Response ◽  
Work Piece ◽  
Static And Dynamic Characteristics ◽  
Five Axis ◽  
Speed Accuracy ◽  
Machine Structure

Abstract With the development of machine tools trending toward high precision, intelligence, multi-axis, and high speed, the improvement of the processing performance and rigidity of the machine is considerably important. The objective of this study is to design of a high-speed five-axis moving-column machine tool and perform structural analysis and optimization. We study the static and dynamic characteristics of the five-axis machine tool, design and improve the mechanical structure, and optimize the structural configuration of the machine. The entire machine structure is further analyzed and enhanced to improve its static and dynamic characteristics, including static rigidity, modal, transient, and spectral response characteristics. The static and dynamic characteristics of the machine structure directly affect the machine processing performance, and further affect the work piece precision machined by the tool. Through this study, the design technology for speed, accuracy, and surface roughness of the machine tool are further improved.

scholarly journals Determination of Material and Failure Characteristics for High-Speed Forming via High-Speed Testing and Inverse Numerical Simulation

2020 ◽  
Vol 4 (2) ◽  
pp. 31 ◽  
Author(s):  
Verena Psyk ◽  
Christian Scheffler ◽  
Marc Tulke ◽  
Sven Winter ◽  
Christina Guilleaume ◽  
...  
Keyword(s):  
High Speed ◽  
Uniaxial Tensile ◽  
Material Parameters ◽  
Dependent Rate ◽  
High Speed Forming ◽  
Numerical Process ◽  
Production Technologies ◽  
Stress States ◽  
Static Conditions

In conventional forming processes, quasi-static conditions are a good approximation and numerical process optimization is the state of the art in industrial practice. Nevertheless, there is still a substantial need for research in the field of identification of material parameters. In production technologies with high forming velocities, it is no longer acceptable to neglect the dependency of the hardening on the forming speed. Therefore, a method for determining material characteristics in processes with high forming speeds was developed by designing and implementing a test setup and an inverse parameter identification. Two acceleration concepts were realized: a pneumatically driven one and an electromagnetically driven one. The method was verified for a mild steel and an aluminum alloy proving that the identified material parameters allow numerical modeling of high-speed processes with good accuracy. The determined material parameters for steel show significant differences for different stress states. For specimen geometries with predominantly uniaxial tensile strain at forming speeds in the order of 104–105/s the determined yield stress was nearly twice as high compared to shear samples; an effect which does not occur under quasi-static loading. This trend suggests a triaxiality-dependent rate dependence, which might be attributed to shear band induced strain localization and adiabatic heating.

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 The Method of Accurate Determination of Frequencies and Modes of Vibration of the Resonator of the Vibration Frequency Sensor

2019 ◽  
pp. 16-21
Author(s):  
O. Oliynyk ◽  
Y. Taranenko
Keyword(s):  
Vibration Frequency ◽  
Accurate Determination ◽  
Accurate Method ◽  
Approximate Methods ◽  
Design Work ◽  
Frequency Sensor ◽  
Modes Of Vibration ◽  
Basic Equations ◽  
The Ideal

The article is devoted to the development of an accurate method for determining the frequencies and vibration modes of a resonator of a vibration-frequency sensor by applying an exact simplification of the basic equations of resonant oscillations of a resonator taking into account the rigidity (compliance) of the supports and their location. The deviation of the parameters of the geometry of the resonator from the ideal and the heterogeneity of the material of the resonator affect the metrological characteristics of the vibration frequency sensor. However, existing technologies do not provide the possibility of manufacturing resonators with nominal parameters. The existing numerous algorithms for calculating the frequencies and waveforms of resonators are used to estimate the fundamental frequency of an oscillating system that do not take into account the dynamic characteristics. The accuracy of the oscillation frequency of the resonator depends on the choice of the mode of oscillations, which is sometimes difficult to predict in advance. Practical tasks require performing design work with the required accuracy. The lack of an accurate method for determining the frequencies and modes of vibration of the resonator of the vibration-frequency sensor, which would take into account the type of mounting and location of resistance, designers have to adapt existing approaches and calculation models to specific measurement conditions. Therefore, in practice, simplified and approximate methods of calculation are used. In the presence of concentrated masses and in the case of taking into account energy dissipation in the places where the resonator is fixed, the calculation methods become more laborious. In some cases, the possibility of a mathematical interpretation of a task becomes feasible only if some simplifications are introduced into the calculation.

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.

scholarly journals Effect of Time-Varying Moving Structures on the Spatial Accuracy of Five-Axis Machine Tools

2021 ◽  
Author(s):  
Tzu-Chi Chan ◽  
Jyun-Sian Yang
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
High Speed ◽  
Time Varying ◽  
Spatial Accuracy ◽  
Static And Dynamic Characteristics ◽  
Five Axis ◽  
Speed Accuracy ◽  
Machine Structure

Abstract Machine tools are constantly in motion during machining; however, studies have not considered the effect of the dynamic and static characteristics of the machine caused by the movement of the structure over time. In this study, the time-varying moving structure in the spatial coordinate arm is analyzed to improve the spatial accuracy of the motion of a five-axis machine tool in the cutting area. The objective is to design a high-speed five-axis moving-column machine tool and to perform structural analysis of spatial accuracy. We studied the static and dynamic characteristics of a five-axis machine tool, designed and improved its mechanical structure, and optimized its structural configuration. With further analysis, the entire machine structure was enhanced to improve its static and dynamic characteristics. The static and dynamic characteristics of the machine structure were found to directly affect its processing performance and the precision of the workpiece machined by the tool. Through this study, the design technology for speed, accuracy, and surface roughness of the machine tool was further improved.

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