Moving Load on a Laminated Composite

1974 ◽  
Vol 41 (3) ◽  
pp. 663-667 ◽  
Author(s):  
C. Sve ◽  
G. Herrmann
Keyword(s):  
Dynamic Response ◽  
Half Plane ◽  
Moving Load ◽  
Formal Solution ◽  
Laminated Composite ◽  
Laplace Transforms ◽  
Layered Material ◽  
Effective Stiffness ◽  
Far Field ◽  
Numerical Examples

A solution is presented for the dynamic response of a periodically laminated half plane that consists of alternating layers of two different materials and is subjected to a moving load. The laminations are parallel to the surface of the half plane, and the velocity of the load is steady and supersonic. An effective stiffness theory developed by Sun, Achenbach, and Herrmann is used to model the layered material, and the formal solution is obtained with the aid of Laplace transforms. A far-field solution is constructed with the head-of-the-pulse procedure, and several numerical examples are presented.

A new technique for right half plane zero elimination from dynamics of a boost converter using magnetic coupling concept

Circuit World ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alireza Goudarzian
Keyword(s):  
Dynamic Response ◽  
Half Plane ◽  
Phase Structure ◽  
Voltage Regulation ◽  
Boost Converter ◽  
Open Loop ◽  
Positive Zero ◽  
Voltage Gain ◽  
Minimum Phase ◽  
Content Type

Purpose Control-signal-to-output-voltage transfer function of the conventional boost converter has at least one right-half plane zero (RHPZ) in the continuous conduction mode which can restrict the open-loop bandwidth of the converter. This problem can complicate the control design for the load voltage regulation and conversely, impact on the stability of the closed-loop system. To remove this positive zero and improve the dynamic performance, this paper aims to suggest a novel boost topology with a step-up voltage gain by developing the circuit diagram of a conventional boost converter. Design/methodology/approach Using a transformer, two different pathways are provided for a classical boost circuit. Hence, the effect of the RHPZ can be easily canceled and the voltage gain can be enhanced which provides conditions for achieving a smaller working duty cycle and reducing the voltage stress of the power switch. Using this technique makes it possible to achieve a good dynamic response compared to the classical boost converter. Findings The observations show that the phase margin of the proposed boost converter can be adequately improved, its bandwidth is largely increased, due to its minimum-phase structure through RHPZ cancellation. It is suitable for fast dynamic response applications such as micro-inverters and fuel cells. Originality/value The introduced method is analytically studied via determining the state-space model and necessary criteria are obtained to achieve a minimum-phase structure. Practical observations of a constructed prototype for the voltage conversion from 24 V to 100 V and various load conditions are shown.

scholarly journals The uncertainty in stiffness and damping of an automotive vehicle’s trim-structure mounts and its effect on the variability of the vibration transfer function

2017 ◽  
Vol 232 (15) ◽  
pp. 2587-2598 ◽  
Author(s):  
Ali Abolfathi ◽  
Dan J O’Boy ◽  
Stephen J Walsh ◽  
Amy M Dowsett ◽  
Stephen A Fisher
Keyword(s):  
Boundary Condition ◽  
Transfer Function ◽  
Dynamic Response ◽  
Transfer Functions ◽  
Effective Stiffness ◽  
3D Printer ◽  
Structural Elements ◽  
Test Rig ◽  
Manufacturing Tolerances ◽  
Stiffness And Damping

A large number of plastic clips are used in an automotive vehicle to connect the trim to the structure. These are small clips with very small masses compared to the structural elements that they connect together; however, the uncertainty in their properties can affect the dynamic response. The uncertainty arises out of their material and manufacturing tolerances and more importantly the boundary conditions. A test rig has been developed that can model the mounting condition of the clips. This allows measurement of the range of their effective stiffness and damping. Initially, the boundary condition at the structure side is replicated. The variability is found to be 7% for stiffness and 8% for damping. In order to simulate the connection of the trim side, a mount is built using a 3D printer. The variability due to the boundary condition on both sides was as large as 40% for stiffness and 36% for damping. A Monte Carlo simulation is used in order to assess the effect of the uncertainty of the clips’ properties on the vibration transfer functions of a door assembly. A simplified connection model is used in this study where only the axial degree of freedom is considered in connecting the trim to the door structure. The uncertainty in the clip stiffness and damping results in a variability in the vibration transfer function which is frequency dependent and can be as high as 10% at the resonant peaks with higher values at some other frequencies. It is shown that the effect of the uncertainty in the clips effective damping is negligible and the variability in the dynamic response is mainly due to the uncertainty in the clip’s stiffness. Furthermore, it is shown that the variability would reduce either by increasing or decreasing the effective stiffness of the clips.

scholarly journals Spectral analysis of multiple cracked beam subjected to moving load

2014 ◽  
Vol 36 (4) ◽  
pp. 245-254
Author(s):  
N. T. Khiem ◽  
P. T. Hang
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Time History ◽  
Theoretical Development ◽  
Multiple Cracks ◽  
Spectral Approach ◽  
Cracked Beam ◽  
Time History Response ◽  
Numerical Case Study

In present paper, the spectral approach is proposed for analysis of multiple cracked beam subjected to general moving load that allows us to obtain explicitly dynamic response of the beam in frequency domain. The obtained frequency response is straightforward to calculate time history response by using the FFT algorithm and provides a novel tool to investigate effect of position and depth of multiple cracks on the dynamic response. The analysis is important to develop the spectral method for identification of multiple cracked beam by using its response to moving load. The theoretical development is illustrated and validated by numerical case study.

scholarly journals Track Dynamic Response At Low Frequencies – Dominant Frequencies

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Milan Moravčík ◽  
Martin Moravčík
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Low Frequency ◽  
Track Structure ◽  
Dynamic Effects ◽  
Low Frequencies ◽  
Frequency Area ◽  
Dominant Frequencies ◽  
40 Hz

Abstract The paper is devoted dynamic effects in the track structure - the quasi-static excitation due to moving load, as the important source for the response of track components in the low frequency area (0 Hz < f < 40 Hz). The low-frequency track (the rail) response is associated with periodicity of wheel sets, bogies, and carriages of passage trains, The periodicity of track loading is determined by so called dominant frequencies f(d) at a position x of the track.

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