An Investigation on the Dynamic Response Property in an Underground Tunnel Space with Constant Temperature

In the present paper the model of beam on Winkler-type elastic foundation is used to model the underground tunnel. The soil displacement (mm)-stress (kpa) curve (p-s curve) is approximated in the form of hyperbolic type function by fitting the existing experimental data and then equivalent linear type of nonlinear bedding coefficient of foundation is derived from the fitting curve. Substitute the equivalent coefficient into the vibration equation of beam on Winkler-type elastic foundation, and we may assess the nonlinear effect of soil. Based on the hypothesis of large distance to earthquake source, Rayleigh wave is used to simulate the longitudinal shearing seismic wave. According to the amplitude attenuation law of Rayleigh wave in elastic half place, the effect of structure bury depth on dynamic response of underground tunnel is considered and the conception of critical bury depth is put forward. Finally the vibration differential equation of beam on Winkler-type elastic foundation is solved by using Matlab software, and the dynamic response of underground tunnel at different structure bury depth are compared. The results may provide a reference for practical engineering.

Download Full-text

Vibrations Caused By Train Passages In Underground Tunnel Compared To Vibrations From Ground Surface Transportation – Some Results Of Investigations

Archives of Civil Engineering ◽

10.2478/ace-2014-0018 ◽

2014 ◽

Vol 60 (2) ◽

pp. 269-286

Author(s):

Krzysztof Stypuła

Keyword(s):

Dynamic Response ◽

Ground Surface ◽

Experimental Investigations ◽

Ground Vibrations ◽

Underground Tunnel ◽

Surface Transportation

Abstract The paper describes experimental investigations of vibrations caused by train passages in the shallow underground tunnel (in Warsaw, Poland) in comparison to the results of measurements of vibrations from ground surface transportation (trams and buses). Propagation of surface ground vibrations from underground tunnel is presented. The problem of dynamic response of a building and influence of vibrations caused by underground on people residing in a building is discussed as well. The dynamic response of the building to underground vibrations is essentially different from the response of a building excited by surface sources of transport vibrations. Also the distribution of influence of the transport vibrations on people in the building is significantly different in both cases.

Download Full-text

PDMS-Based Capacitive Pressure Sensor for Flexible Transparent Electronics

Journal of Sensors ◽

10.1155/2019/1418374 ◽

2019 ◽

Vol 2019 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Longlong Chen ◽

Xin Chen ◽

Zhihan Zhang ◽

Tongkuai Li ◽

Tingting Zhao ◽

...

Keyword(s):

Dynamic Response ◽

Pressure Sensor ◽

Annealing Temperature ◽

Curing Temperature ◽

Response Property ◽

Capacitive Pressure Sensor ◽

Pdms Film ◽

Compression Property ◽

Sensing Applications ◽

Bending Radius

We propose a flexible pressure sensor based on polydimethylsiloxane (PDMS) and transparent electrodes. The transmittance of the total device is 82% and the minimum bending radius is 18 mm. Besides, the effect of annealing temperature on the mechanical properties of PDMS is reported here. The results show that the PDMS film under lower annealing temperature of 80°C has good compression property but poor dynamic response. While for higher temperatures, the compression property of PDMS films significantly reduced. The best compromise of annealing temperature between compression property and dynamic response is found for PDMS film of about 110°C. The pressure sensor under 110°C curing temperature shows a good sensitivity of 0.025 kPa−1 and robust response property. The device shows a promising route for future intelligent transparent sensing applications.

Download Full-text

Model Creation and Parameter Identification of Gun-Shoulder System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.960 ◽

2011 ◽

Vol 121-126 ◽

pp. 960-963

Author(s):

Jian Dong Bao ◽

Chang Ming Wang

Keyword(s):

Dynamic Response ◽

Parameter Identification ◽

Mechanical Impedance ◽

Response Property ◽

Characteristic Parameters ◽

Model Parameter ◽

Mechanics Model ◽

Inherent Characteristic ◽

Impedance Property

This paper analyzed mechanical admittance for contacting point between gun and shoulder; identified inherent characteristic parameters, established model of gun-shoulder system base on plentiful experiments. The results that can not only reflect mechanical impedance property of the shoulder, but also embody the equivalent dynamic response property of man-gun system. Then, making statistics analyses for different shooter, confirming receiving-shoulder’s model parameter of man-gun, providing academic base for building mechanics model of man-gun.

Download Full-text