Application of Frequency Method for Defining Threaded Joint Tightening Degree

2006 ◽  
Vol 113 ◽  
pp. 277-280
Author(s):  
Vytautas Kazimieras Augustaitis ◽  
Vytautas Bučinskas ◽  
V. Pauža
Keyword(s):  
Transient Process ◽  
Internal Combustion Engines ◽  
Dynamic Properties ◽  
Contact Stiffness ◽  
Frequency Method ◽  
Threaded Joint ◽  
Resonance Frequencies ◽  
Threaded Joints ◽  
Joint Tightening ◽  
Computer Card

There is a big variety of machines and equipment – internal combustion engines, aviation parts, building frames - joined by threaded joints, realized as bolt, nut and pin ones. For successful and safe exploitation of such equipment, it is required to check the tightening degree of threaded joints. There are few known methods of such control and one is presented in this paper. The proposed method is based on contact stiffness and friction change from thread tightening degree. At the same time, tightening changes with sufficient significance the dynamical properties of such a system - natural and resonance frequencies, amplitude – frequency and amplitude-phase characteristics, so, that it is possible to evaluate the tightening degree of the investigated joint. Dynamic properties are defined by exciting transient process between bolt head and tightened by this bolt detail using as short as possible force impact. Sensors register analogical signal of transient process and transmit it to a special computer card. The computer card converts analogical signal to code. Code is saved in the computer file for further processing. Processing data is saved in this file, and we find desired dynamical characteristics. Using special experimental bench proved that dynamic characteristics are sensitive enough to threaded joint tightening degree and the method is applicable to practice.

scholarly journals Designing of Drive Systems in the Aspect of the Desired Spectrum of Operation

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2562
Author(s):  
Tomasz Dzitkowski ◽  
Andrzej Dymarek ◽  
Jerzy Margielewicz ◽  
Damian Gąska ◽  
Lukasz Orzech ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Dynamic Parameters ◽  
Synthesis Algorithm ◽  
Moments Of Inertia ◽  
Driving System ◽  
Six Degrees Of Freedom ◽  
Resonance Frequencies ◽  
Drive Systems ◽  
Power Component

A method for selecting dynamic parameters and structures of drive systems using the synthesis algorithm is presented. The dynamic parameters of the system with six degrees of freedom, consisting of a power component (motor) and a two-speed gearbox, were determined, based on a formalized methodology. The required gearbox is to work in specific resonance zones, i.e., meet the required dynamic properties such as the required resonance frequencies. In the result of the tests, a series of parameters of the drive system, defining the required dynamic properties such as the resonance and anti-resonance frequencies were recorded. Mass moments of inertia of the wheels and elastic components, contained in the required structure of the driving system, were determined for the selected parameters obtained during the synthesis.

Lorentz Contact Resonance Imaging for Atomic Force Microscopes: Probing Mechanical and Thermal Properties on the Nanoscale

2013 ◽  
Vol 21 (6) ◽  
pp. 18-24 ◽  
Author(s):  
Eoghan Dillon ◽  
Kevin Kjoller ◽  
Craig Prater
Keyword(s):  
Viscoelastic Properties ◽  
Contact Stiffness ◽  
Mechanical And Thermal Properties ◽  
Resonance Modes ◽  
Atomic Force ◽  
Resonance Frequencies ◽  
Other Information ◽  
Afm Cantilever ◽  
Stiffness And Damping ◽  
Contact Resonance

Atomic force microscopy (AFM) has been widely used in both industry and academia for imaging the surface topography of a material with nanoscale resolution. However, often little other information is obtained. Contact resonance AFM (CR-AFM) is a technique that can provide information about the viscoelastic properties of a material in contact with an AFM probe by measuring the contact stiffness between the probe and sample. In CR-AFM, an AFM cantilever is oscillated, and the amplitude and frequency of the resonance modes of the cantilever are monitored. When a probe or sample is oscillated, the tip sample interaction can be approximated as an ideal spring-dashpot system using the Voigt-Kelvin model shown in Figure 1. Contact resonance frequencies of the AFM cantilever will shift depending on the contact stiffness, k, between the tip and sample. The damping effect on the system comes from dissipative tip sample forces such as viscosity and adhesion. Damping, η, is observed in a CR-AFM system by monitoring the amplitude and Q factor of the resonant modes of the cantilever. This contact stiffness and damping information can then be used to obtain information about the viscoelastic properties of the material when fit to an applicable model.

scholarly journals Effect of Grain Refinement on the Dynamic, Mechanical Properties, and Corrosion Behaviour of Al-Mg Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1825
Author(s):  
Haitham M. Ahmed ◽  
Hussin A. M. Ahmed ◽  
Mohammed Hefni ◽  
Essam B. Moustafa
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Corrosion Behaviour ◽  
Cast Alloy ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Xrd Analysis ◽  
Optical Microscope ◽  
Mg Alloy ◽  
Resonance Frequencies

In this investigation, aluminium Al-2.5% Mg cast alloy was modified by adding 0.5 Ti and 0.1 B wt % modifiers to investigate their impact on the dynamic behaviour, as well as the mechanical and microstructure properties. The dynamic properties were analysed experimentally using a free vibration impact test and predicted using finite element methods. This study used a high-resolution polarised optical microscope to analyse the microstructure of the studied alloys and X-ray Powder Diffraction (XRD) analysis to determine the developed phases. Microstructure and mechanical properties were mostly enhanced as a result of grain refining during solidification and through the metal segregation process. The microstructure analysis of the modified alloy showed a significant improvement in the grain refinement; hence, the grains were 10 times finer than the cast alloy. The modified Al-2.5% Mg/Ti-B alloy demonstrated reduced inter-granular corrosion (IGC) than the Al-2.5% Mg standard cast alloy. By incorporating Ti-B modifiers into the composition of the cast Al-Mg alloy, the ultimate tensile strength (UTS), strain (ε), and hardness values (HV) were increased by 30.5%, 100%, and 18.18%, respectively. The dynamic properties of the modified alloy showed an enhancement in the resonant (fn) and damping ratio (ζ) by 7% and 68%, respectively. The predicted resonance frequencies of the investigated alloys showed results close to the experimental dynamic tests.

Influence of the Supplementary Cementitious Materials on the Dynamic Properties of Concrete

2014 ◽  
Vol 660 ◽  
pp. 162-167
Author(s):  
Elbachir Elbahi ◽  
Sidi Mohammed El Amine Boukli Hacene
Keyword(s):  
Dynamic Modulus ◽  
Dynamic Properties ◽  
Construction Materials ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Natural Pozzolan ◽  
Frequency Method ◽  
Concrete Mixtures ◽  
And Control ◽  
Non Destructive

The resonance frequency method is one of many non-destructive tests which allow us to evaluate construction materials. It was used to determine the dynamic properties of concrete, required in structures design and control, also considered as the key elements for materials dynamic. In this study, we chose a non-destructive approach to quantify-in laboratory-, the influence of adding “crushed limestone” and “natural pozzolan” on local concrete’s dynamic characteristics. However, several concrete mixtures have been prepared with limestone aggregates. The experimental used plan, allowed us to determine the dynamic modulus of elasticity, the dynamic modulus of rigidity of different formulated concretes.

Impact Test in Working Space of Milling Center

2012 ◽  
Vol 463-464 ◽  
pp. 81-84
Author(s):  
Doina Marin ◽  
Nicolae Predincea ◽  
Dan Mihail Marin
Keyword(s):  
Impact Test ◽  
Dynamic Properties ◽  
Work Piece ◽  
Technical Problems ◽  
Working Space ◽  
Resonance Frequencies ◽  
Excited Vibration ◽  
Comparative Results ◽  
Clamping Device ◽  
Impulse Force

Experimental modal analysis is quickly developed area of science in last years. Experimental approach for solving technical problems is a means to estimate or evaluate modal properties of a mechanical structure. The paper is focused at dynamic properties of milling centers, namely at the resonance frequencies and vibration shapes of a simplified tool-work piece system. All this properties are identified by measurements. The machine tool vibration was excited by impulse force and a response of excited vibration was recorded. The measurement points for vibration were selected at the spindle head, the table and the clamping device. The paper aims to present comparative results of theoretical studies with experimental results obtained from impact test to the machining centers.

scholarly journals An overview on the seismic microzonation and site effect studies in Central Asia

2015 ◽  
Vol 58 (1) ◽  
Author(s):  
Marco Pilz ◽  
Tanatkan Abakanov ◽  
Kanatbek Abdrakhmatov ◽  
Dino Bindi ◽  
Tobias Boxberger ◽  
...  
Keyword(s):  
Central Asia ◽  
Seismic Noise ◽  
Dynamic Properties ◽  
Site Response ◽  
Site Effect ◽  
Seismic Zonation ◽  
Progressive Development ◽  
Array Measurements ◽  
Resonance Frequencies ◽  
Seismic Networks

<p>During the past centuries, many cities in Central Asia have suffered significant damages caused by earthquakes. A crucial step towards preparedness for future events, the definition of the optimal engineering designs for civil structures and the mitigation of earthquake risks involves the accomplishment of site response studies. To accurately identify local variations of the site response at different locations within the cities, earthquakes recorded by seismic networks as well as measurements of the seismic noise can be used for estimating the resonance frequencies and for evaluating the expected level of ground motion at each site. Additionally, the measurements can help identifying site specific features like more-dimensional resonances and directional effects. This information can be complemented with array measurements of ambient seismic noise in order to estimate local shear-wave velocity profiles, an essential parameter for evaluating the dynamic properties of soil, and to characterize the corresponding sediment layers at each site. The present study gives an overview on the progressive development of the seismic zonation studies in the frame of EMCA carried out in several cities in Central Asia.</p>

Contact Stiffness of New and Worn Surfaces

2005 ◽  
Author(s):  
A. Soom ◽  
C. I. Serpe
Keyword(s):  
Unit Area ◽  
Contact Stiffness ◽  
Measured Data ◽  
Wear Particles ◽  
Subsurface Cracks ◽  
Nominal Pressure ◽  
Resonance Frequencies ◽  
Area Basis ◽  
Steel Surfaces ◽  
Rough Surface Contact

The presence of surface texture/roughness on engineering surfaces results in contacts between surfaces being considerably more compliant than if the interfaces were smooth and flat. The inclusion of a local contact stiffness can be critical to the accurate analytical or computational modeling of mechanical contacts. We present measurements of contact stiffness for five pairs of freshly prepared and worn of steel surfaces. The wom surfaces variously contain surface glazes, oxide layers, subsurface cracks, inclusions and wear particles. Contact resonance frequencies between sample interfaces are measured at various applied pressures. With known modal masses, the contact stiffness is easily calculated and presented on a per unit area basis. For a given contact pair, the contact stiffness is nonlinear, increasing with nominal pressure and decreasing with increasing surface roughness. We compare these results with the Greenwood-Williamson (G-W) Theory of rough surface contact. The expected pressure and summit height dependencies are observed in the measured data. When there are wear particles within the contact, the stiffness is reduced when the underlying surfaces are very smooth. If the underlying surfaces are rough, the presence of wear particles have little effect on the contact stiffness.

Simplified models to represent human effects on floor dynamic properties

2021 ◽  
Author(s):  
Mehdi Setareh
Keyword(s):  
Dynamic Systems ◽  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Human Subjects ◽  
Response Functions ◽  
Simplified Models ◽  
Resonance Frequencies ◽  
Floor Vibrations ◽  
Human Effects ◽  
Vibration Tests

<p>Human activities such as walking, jogging, and running can cause excessive floor vibrations in buildings, footbridges, etc. It is known that humans act as dynamic systems modifying floor properties. A series of vibration tests with a number of human subjects were conducted on test floors through which the human dynamic properties were measured using simplified single and two- degrees-of-freedom models by minimizing the error between the predicted and measured resonance frequencies and resonance frequency response functions. The tests were conducted with the human subjects in standing, sitting, and bent-knees postures. The resulting models were used to predict the floor resonance frequencies and damping ratios. These values were found to be close to those from the measurements which validated the simplified human models used.</p>

scholarly journals Simulation of Payne Effect of Elastomeric Isolators with a Harmonic Balance Method

2012 ◽  
Vol 19 (6) ◽  
pp. 1281-1295 ◽  
Author(s):  
V. Jaumouillé ◽  
J.-J. Sinou ◽  
B. Petitjean
Keyword(s):  
Harmonic Balance ◽  
Strain State ◽  
Dynamic Properties ◽  
Harmonic Balance Method ◽  
Equivalent Strain ◽  
Complex Model ◽  
Balance Method ◽  
Payne Effect ◽  
Resonance Frequencies ◽  
Non Linear

In the presented work, a non linear effect of rubber referred as Fletcher-Gent effect or Payne effect is investigated. It leads to a change in the rubber dynamic modulus with vibration amplitudes and, consequently, modifies resonance frequencies of mechanical systems including non linear elastomers. In this study a new methodology is developed to take into account Payne effect in a linear viscoelastic rubber material. Small vibration amplitudes around a no-preloaded state are predicted by considering frequency and amplitude dependencies of the material. This methodology has the advantage of using tabular experimental data from characterization tests which avoids the development of a complex model. In order to compute frequency responses, the non linear harmonic balance method is used and, for each iteration, new rubber properties are affected at each element according to its strain state. An equivalent strain measure is evaluated from the element strain energy density. This equivalent strain allows to associate dynamic properties of a material element subjected to multiaxial strain state with experimental dynamic properties of a material sample subjected to an uniaxial strain state. Practically, DMAP alter procedures are developed in order to evaluate energies in models defined with MSC.Nastran and the non linear solver is developed with Matlab. The method is applied on a satellite instrument isolator including four non linear rubber mounts. A non homogeneous spatial distribution of element equivalent strains is observed. Moreover, the maximum equivalent strain varies with frequency. These two observations validate the use of a specific methodology to deal with amplitude dependency of rubber.

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