Vibration Properties of Rubberlike Materials

1942 ◽  
Vol 34 (11) ◽  
pp. 1358-1365 ◽  
Author(s):  
R. B. Stambaugh
Keyword(s):  
Vibration Properties ◽  
Rubberlike Materials

Vibration Properties of Rubberlike Materials Dependence on Temperature

1943 ◽  
Vol 16 (2) ◽  
pp. 400-416 ◽  
Author(s):  
R. B. Stambaugh
Keyword(s):  
Internal Friction ◽  
Natural Rubber ◽  
Critical Temperatures ◽  
Cohesive Forces ◽  
Exponential Law ◽  
Vibration Properties ◽  
Inverse Effect ◽  
Similar Materials ◽  
Straight Lines ◽  
Rubberlike Materials

Abstract 1. The vibration modulus and resilience are independent of the frequency of vibration if the temperature is constant. 2. The internal friction is approximately inversely proportional to the frequency. 3. The modulus decreases as temperature increases. Curves for synthetic stocks at high temperatures are not very different from those of rubber at low temperatures. 4. Resilience rises linearly with temperature. Rubber shows a transition from one slope to another at about 25° C. 5. The dependence of the internal friction of rubber and similar materials on temperature follows the same exponential law as the viscosity of liquids. At certain critical temperatures sudden changes occur in the cohesive forces, which cause a transition from one curve to another. For the natural rubber sample this occurs at about 17° C. 6. The amplitude of vibration has a large inverse effect on the modulus and friction, which cannot be explained by the temperature rise of the sample due to heat generated in it. The effect may be due to nonlinearity of the stress-strain curves. 7. Modulus and friction are affected by temperature in the same way, indicating the dependence of both on some fundamental characteristic of the molecular structure. Natural rubber requires two straight lines for representation on the modulus-friction plot, the junction occurring at about 25° C.

scholarly journals Vibration of Rotating and Revolving Planet Rings with Discrete and Partially Distributed Stiffnesses

2020 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Fuchun Yang ◽  
Dianrui Wang
Keyword(s):  
High Speed ◽  
Differential Operators ◽  
Natural Frequencies ◽  
Rotation Speed ◽  
Distribution Area ◽  
Vibration Modes ◽  
Governing Equations ◽  
Vibration Properties ◽  
Wide Range ◽  
Forced Responses

Vibration properties of high-speed rotating and revolving planet rings with discrete and partially distributed stiffnesses were studied. The governing equations were obtained by Hamilton’s principle based on a rotating frame on the ring. The governing equations were cast in matrix differential operators and discretized, using Galerkin’s method. The eigenvalue problem was dealt with state space matrix, and the natural frequencies and vibration modes were computed in a wide range of rotation speed. The properties of natural frequencies and vibration modes with rotation speed were studied for free planet rings and planet rings with discrete and partially distributed stiffnesses. The influences of several parameters on the vibration properties of planet rings were also investigated. Finally, the forced responses of planet rings resulted from the excitation of rotating and revolving movement were studied. The results show that the revolving movement not only affects the free vibration of planet rings but results in excitation to the rings. Partially distributed stiffness changes the vibration modes heavily compared to the free planet ring. Each vibration mode comprises several nodal diameter components instead of a single component for a free planet ring. The distribution area and the number of partially distributed stiffnesses mainly affect the high-order frequencies. The forced responses caused by revolving movement are nonlinear and vary with a quasi-period of rotating speed, and the responses in the regions supported by partially distributed stiffnesses are suppressed.

scholarly journals Ambient Vibration Tests of an Arch Dam with Different Reservoir Water Levels: Experimental Results and Comparison with Finite Element Modelling

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Sergio Vincenzo Calcina ◽  
Laura Eltrudis ◽  
Luca Piroddi ◽  
Gaetano Ranieri
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Water Levels ◽  
Arch Dam ◽  
Experimental Results ◽  
Ambient Vibration ◽  
Reservoir Water ◽  
Ambient Vibration Tests ◽  
Vibration Properties ◽  
Vibration Tests

This paper deals with the ambient vibration tests performed in an arch dam in two different working conditions in order to assess the effect produced by two different reservoir water levels on the structural vibration properties. The study consists of an experimental part and a numerical part. The experimental tests were carried out in two different periods of the year, at the beginning of autumn (October 2012) and at the end of winter (March 2013), respectively. The measurements were performed using a fast technique based on asynchronous records of microtremor time-series. In-contact single-station measurements were done by means of one single high resolution triaxial tromometer and two low-frequency seismometers, placed in different points of the structure. The Standard Spectral Ratio method has been used to evaluate the natural frequencies of vibration of the structure. A 3D finite element model of the arch dam-reservoir-foundation system has been developed to verify analytically determined vibration properties, such as natural frequencies and mode shapes, and their changes linked to water level with the experimental results.

scholarly journals Vibration Properties of a Concrete Structure with Symmetries Used in Civil Engineering

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 656
Author(s):  
Sorin Vlase ◽  
Marin Marin ◽  
Ovidiu Deaconu
Keyword(s):  
Dynamic Analysis ◽  
Concrete Structure ◽  
Current Practice ◽  
Civil Engineering ◽  
Engineering Practice ◽  
Design Time ◽  
Vibration Properties ◽  
Reduced Costs ◽  
Constructive Simplicity ◽  
Economic Considerations

The paper aims to study a concrete structure, currently used in civil engineering, which has certain symmetries. This type of problem is common in engineering practice, especially in civil engineering. There are many reasons why structures with identical elements or certain symmetries are used in industry, related to economic considerations, shortening the design time, for constructive, simplicity, cost or logistical reasons. There are many reasons why the presence of symmetries has benefits for designers, builders, and beneficiaries. In the end, the result of these benefits materializes through short execution times and reduced costs. The paper studies the eigenvalue and eigenmode properties of vibration for components of the constructions’ structure, often encountered in current practice. The identification of such properties allows the simplification and easing of the effort necessary for the dynamic analysis of such a structure.

The Modelling of the Opening and Closure of a Crack

1995 ◽  
Vol 117 (3A) ◽  
pp. 370-377 ◽  
Author(s):  
O. N. L. Abraham ◽  
J. A. Brandon
Keyword(s):  
Fourier Series ◽  
Cantilever Beam ◽  
Time Domain ◽  
Dry Friction ◽  
Transverse Crack ◽  
Normal Modes ◽  
Time Varying ◽  
Interaction Forces ◽  
Vibration Properties ◽  
Connection Matrices

The paper presents a method which utilizes substructure normal modes to predict the vibration properties of a cantilever beam with a breathing transverse crack. The two segments of the cantilever beam, separated by the crack, are related to one another by time varying connection matrices representing the interaction forces. The connection matrices are expanded in a Fourier series leading to a classical eigenvalue problem. Subsequently, the initial formulation is extended to avoid interference of the crack interfaces with a time domain formulation. The Lagrange multipliers, used to enforce the exact continuity constraints when the crack is closed, produce the interfaces forces needed for the modelling of interface dry friction.

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