Acoustics. Method for the determination of dynamic stiffness.

1992 ◽  
Keyword(s):  
Dynamic Stiffness

Technical Note: Rolling dynamic stiffness and damping characteristics of small-sized pneumatic tyres

2000 ◽  
Vol 214 (3) ◽  
pp. 243-248 ◽  
Author(s):  
V. H. Saran ◽  
V. K. Goel
Keyword(s):  
Normal Load ◽  
Dynamic Stiffness ◽  
Technical Note ◽  
Inflation Pressure ◽  
Laboratory Technique ◽  
Damping Coefficients ◽  
Damping Characteristics ◽  
Stiffness And Damping

In this paper, a laboratory technique for determination of rolling dynamic stiffness and damping coefficients of small-sized, bias-ply tyres has been discussed. The effect of normal load, inflation pressure and speed on four different tyres has been reported. The results show similar trends to those reported by other investigators.

scholarly journals Improvement of Comfort in Suspension Seats with a Pneumatic Negative Stiffness System

Actuators ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 126
Author(s):  
Eduardo Palomares ◽  
Angel L. Morales ◽  
Antonio J. Nieto ◽  
Jose M. Chicharro ◽  
Publio Pintado
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Nonlinear Dynamic System ◽  
Negative Stiffness ◽  
Vehicle Model ◽  
Seat Suspension ◽  
Highly Nonlinear ◽  
Linear Actuators ◽  
Static Conditions

This paper presents a Negative Stiffness System (NSS) for vibration isolation and comfort improvement of vehicle seats, which enhances the performance of optimized traditional passive seat suspensions. The NSS is based on a set of two Pneumatic Linear Actuators (PLAs) added to a seat supported by a pneumatic spring. One end of each PLA is joined to the seat while the other end is joined to the vehicle frame. In static conditions, the PLAs remain horizontal, whereas in dynamic conditions, their vertical forces work against the pneumatic spring, reducing the overall dynamic stiffness and improving passenger comfort. The paper presents a stability analysis of the highly nonlinear dynamic system, as well as the numerical determination of the optimum PLA pressure for a given passenger mass that maximises comfort without instabilities. Finally, the performance of the proposed NSS is compared to that of a traditionally optimized passive seat suspension via simulations of an eight-degree-of-freedom vehicle model traversing several road profiles and speed bumps. Comfort improvements between 10% and 35% are found in all tests considered.

scholarly journals Determination of the elastic parameters of a material from a standardized dynamic stiffness testing

2019 ◽  
Vol 460 ◽  
pp. 114885 ◽  
Author(s):  
Enrique G. Segovia-Eulogio ◽  
Jennifer Torres ◽  
Jesús Carbajo ◽  
Jaime Ramis ◽  
Jorge P. Arenas
Keyword(s):  
Dynamic Stiffness ◽  
Elastic Parameters

scholarly journals Free vibration analysis of extension-torsion coupled elements using a dynamic finite element (DFE) formulation

2021 ◽  
Author(s):  
Andrew Roach
Keyword(s):  
Finite Element ◽  
Dynamic Stiffness ◽  
Equations Of Motion ◽  
Laminated Composite ◽  
Free Vibration Analysis ◽  
Structural Members ◽  
Cross Sectional ◽  
Dynamic Finite Element ◽  
Laminated Composite Beams

In this report, the extension-torsion coupled vibration behavior of several structural members is investigated. In order to solve the governing differential equations of motion for the problem, three different approaches, namely the dynamic stiffness matrix (DSM), finite element (FEM), and dynamic finite element (DFE) methods are used. Three different engineering applications of interest are identified, namely, a helical spring, a wire rope and laminated composite beams. For each of these applications, a method for determining the cross-sectional stiffness constants of interest is first introduced. Illustrative examples of each system are then studied where resulting natural frequencies and modes are compared to those available in literature. In order to determine the performance of each solution method in the determination of the dynamic behavior of these systems, all three (DSM, FEM, and DFE) methods are used in the examples, and a comparative study among the results is then carried out to gauge the accuracy of each approach.

The Determination of Dynamic Stiffness of Dish-Shaped Metal Corrugated Pipe by Use of Random Vibration Method

2012 ◽  
Vol 468-471 ◽  
pp. 1393-1397
Author(s):  
Li Ming Rui ◽  
Mei Sheng Zheng ◽  
Lian Jun Tian
Keyword(s):  
Random Vibration ◽  
Dynamic Stiffness ◽  
Static Stiffness ◽  
Mass System ◽  
Single Degree Of Freedom ◽  
Vibration Method ◽  
Single Degree ◽  
Wide Range ◽  
Random Vibration Method

This paper simplifies the dish-shaped metal corrugated pipe into a elastic element, constitutes a single degree of freedom spring-mass system, then applicants the random vibration method to measure its natural frequency, further to calculate the dynamic stiffness of dish-shaped metal corrugated pipe. At the same time its static stiffness test is done. By comparison of two results, static and dynamic stiffness values fit well, and dynamic stiffness is closer to the actual working conditions. Random vibration method for dynamic stiffness is convenient, accurate and has application values in a wide range of engineering.

scholarly journals Dynamic Stiffness of Bituminous Mixtures for the Wearing Course of the Road Pavement—A Proposed Method of Measurement

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1973
Author(s):  
Krzysztof Robert Czech ◽  
Wladyslaw Gardziejczyk
Keyword(s):  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Physical And Mechanical Properties ◽  
Test Stand ◽  
Traffic Load ◽  
Road Noise ◽  
The Road ◽  
Bituminous Mixtures ◽  
Signal Amplifier

Stiffness is an important mechanical characteristic of asphalt mixtures used in the wearing course. It is one of the determining factors in the generation of tyre/road noise. The dynamic stiffness of the upper layer of the road surface depends on the physical and mechanical properties of the materials it is composed of, and traffic load. Determination of dynamic stiffness, both in laboratory conditions and in situ, requires consideration of many other factors. Tests of dynamic properties of road surfaces in field conditions are most often conducted with the help of modal hammers. Impulse excitation results are usually less accurate than those in the application of modal exciters. The test stand was constructed, comprising a tripod, 32-channel and 24-bit data acquisition system, exciter, signal amplifier, impedance head, single-axis piezoelectric accelerometers and a stinger. The test stand and the proposed method of measuring dynamic stiffness do not require the determination of the resonance frequency of the tested specimen and can be used both on various types of bituminous mixtures of varying shape and dimensions, as well as directly on the upper surface of the wearing course of bituminous pavements. The test results showed that the type of bituminous mixture used in the wearing course significantly affects its dynamic stiffness. The dynamic stiffness level of asphalt concrete, stone mastic asphalt and porous asphalt layers was determined to be similar. The addition of rubber granulates significantly reduced its rigidity, which is very beneficial from the point of view of reducing the tyre/road noise.

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