A simplified dynamic model to reveal mechanical characteristic of load wheel and experimental validation
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Dynamic load testing
Digital image correlation
The validity of the dynamic tensile strength in rock materials is problematic in dynamic Brazilian splitting tests. The purpose of this study is to understand the failure law and effectiveness of the dynamic Brazilian disc (BD) test for five different rock types under three typical loading modes, including platform loading (mode-I), steel bar loading (mode-II) and arc loading (mode-III). Based on the digital image correlation (DIC) technique and high-speed camera, the deformation localization and rupture evolution of the BD specimen under impact loading were obtained, and two rupture characteristics of the specimen were summarized. The loading mode significantly affects the crack initiation location of the disc in the dynamic BD test. The experimental results show that loading mode-III is the most consistent with Brazilian test theory in the dynamic BD test, while loading mode-II violates the test principle. At the same incident energy, the loading rate and dynamic tensile strength are functions of loading mode and lithology, which are highest in loading mode-III, followed by loading mode-I, and the lowest in loading mode-II. The strain and displacement field after peak load were extracted by DIC, and it was found that there were four typical failure modes in dynamic BD tests.
Digital image correlation
Digital Image Analysis
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Digital image correlation
Split Hopkinson Pressure Bar
Bar (unit)
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Dynamic load testing
Digital image correlation
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This paper demonstrates the study of a footbridge’s design and also the analysis of the dynamic behaviour of the footbridges due to human-induced dynamic load. The bridges are located in Surabaya. Firstly, the human loading as a vibration source of the footbridge is presented together with the model force of the loadings. The next section is the design of the bridge subjected to dynamic load from British Standard, AASTHO, and Eurocode. Then the dynamic behaviour of the structure is studied using three Tunjungan footbridges as examples. Finally SDOF system is used to calculate the footbridge vibration induced by the human load and this is presented and applied to the Tunjungan footbridges, which it is very helpful to calculate in practice. The conclusion which can be drawn from this study is that the dynamic behaviour should be considered in the design of footbridges due to human-induced loads and using SDOF system is accurate enough to calculate the responses of the structure.
Structural Dynamics
Eurocode
Dynamic load testing
Bridge (graph theory)
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A loaddeformation testing system is established for executing the uniaxialtension testing of the tire rubber in a larger deformation range. The automated grid method, as a effective photomechanical testing technique, is used in this system to measure the larger deformation of tire rubber. The automated grid method has some merits, including the nontouching form, the high accuracy and the ability to get the fullfield deformation information. The experimental results show that the automated grid method is very suitable for the mechanicalbehavior testing of the rubberlike soft materials. And it is also found that in the loadingunloading process, the carbonblackfilled rubber of the tire tread, i.e. the tread rubber, shows the obvious hysteresis, the Mullins effect and the residual deformation. Based on the transversal mean strain data and the corresponding uniaxial mean strain data, it can be concluded that the tread rubber is compressible in the larger deformation range of uniaxial tension, and that its volume ratio is gradually increased along with the increasing uniaxial tension strain.
Hyperelastic material
Uniaxial tension
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The development of improving dynamic performances of loading wheel rubber is introduced in this thesis. Based on traditional formula of tread rubber, the physical and dynamic performances of mixed rubber are studied through setting primary raw rubber and adjusting reinforced filling system and sulfide system. It is demonstrated that the adoption of both soft and hard carbon tread rubber can meet the requirements of mechanical performance. The stretching stress and fatigue-resistent performance are distinctively increased as well. Furthermore, dynamic heat is reduced and aging-resistent performance is greatly improved.
Dynamic stress
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Carbon black filled SBR (styrene-butadiene rubber) is used for tire tread rubber. The filled SBR undergoes dynamic large deformation at abrupt steering. It is important for mechanical analysis of tire to study on the behavior for dynamic large deformation. The aim of this paper is to propose the mechanical model for dynamic large deformation, taking into consideration the results of uniaxial stretch tests at several rates for filled rubber and higher-order structure of rubber, which is chiefly consist of molecular network, entanglement, filler and its bound rubber.
Filler (materials)
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With reference to the deck unit erection crane used in construction of a newly built cable-stayed bridge without backstays with span arrangement(100+35) m in Suzhou City,the sudden skip load is used to simulate the dynamic action of the crane structure at the time the steel girder being hoisted.The finite element method is then used to establish three-dimensional analysis model for the carne,and the dynamic responses of the crane structure under spatial loading are calculated.The effects of hoisting speed when the steel girder is being hoisted on the dynamic responses and dynamic amplification coefficients of the crane structure are studied.The results of the calculations and study provide theoretic basis for dynamic design of deck unit erection crane structures.
Bridge (graph theory)
Dynamic load testing
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SUMMARY SUMMARY The aim of this work is to simulate the dynamic behaviour of a small rubber tyred locomotive, of the type used extensively in British coal mines, running on rough track. Of particular interest in the dynamic field is the effect of a solid rubber tyre on the tangential wheel-rail forces. The tyre also contributes significantly to both lateral and vertical suspension properties. Dynamic simulation of the lateral and vertical vehicle behaviour has been carried out by time stepping numerical integration of the equations of motion for a representative lumped parameter model. Conclusions regarding the profile of this type of rubber tyre can be drawn from the results of this simulation.
Dynamic simulation
Suspension
Critical speed
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The contact between the tire and the road surface causes tread deformation, and using traditional methods to measure tire tread deformation is difficult and time-consuming. Therefore, based on the principle of the digital image correlation method, this paper develops a binocular vision measurement system and realizes the measurement of tire tread deformation through the test bench for tire ground pressure distribution measurement. The related programs of the measurement system, including camera calibration, image matching, and strain fitting, are proposed. The deformation measurement accuracy of the test bench is validated by the sprayed speckle rubber sheet test, and the relative error of the theoretical value and measurement value is within 2%. The tire tread deformation test under static loading conditions was carried out using the test bench, and the tread strain distribution in the contact area was obtained. The analysis of the test results shows that the strain distribution in the contact patch is axisymmetric under static loading conditions. The longitudinal (tire rolling direction) deformation of the tread at the leading edge and the trailing edge area of the contact patch has the largest strain, while the deformation of the shoulder area on both sides of the contact patch is relatively small. For lateral (tire axial direction) deformation, the leading edge and the trailing edge areas of the contact patch are less deformed, and the strain distribution is approximately axisymmetric. The shoulder area of the contact surface has a larger deformation. The tire’s outer shoulder area has a larger deformation than the inside shoulder area, which may be due to the asymmetric tread structure of the tire. For the vertical deformation of the tread, the central area of the tread has the smallest strain, while the surrounding area has a much larger vertical strain.
Contact patch
Digital image correlation
Contact area
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