The Characteristic Transient Response of a Pressurized Cantilever Pipe Subjected to Transverse Impact at Its Tip

Feng Liu,Yuchao Yang,Yuelei Wu

doi:10.1155/2019/4030379

Feng Liu, Yuchao Yang + Show 1 more

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https://doi.org/10.1155/2019/4030379

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Abstract

This paper describes an experimental study on the pure bending mechanical behavior of a pressurized pipe and adoption of a measured moment-curvature relationship under different working conditions in numerical simulations for transient pipe-whip prediction. To describe the effects of pipe contents and internal pressure, the governing equations were derived based on large deformation theory. Bending moment and axial force were uncoupled in the constitutive equation, and an experiment-based relationship between moment and curvature was adopted. The numerical simulations show that the present model can simulate the mechanical processes of elasticity, plastic hardening, and softening behavior in the initial, middle, and late stages of whole response, respectively. In addition, it was shown that kinks may occur at several positions along an empty cantilever pipe due to the collapse of sections under intense dynamic loading. However, this behavior did not occur for the full pressurized pipe, indicating that the contents and internal pressure are able to effectively impede the partial flattening of the pipe section, improving its critical curvature and changing its plastic dynamic response behavior.

Highlights

Pipes for conveying high-energy and high-pressure fluids are widely used in nuclear power plants and petrochemical facilities
In contrast to the well-known elasticplastic hardening phenomenon, this process is always called softening behavior [4]. e second deformation mode of a tube under bending involves buckling on the compressed side of the tube due to excessive compressive stress. e experimental studies of Yu et al [3], Reid et al [4, 5], and Prinja and Chitkara [6] have recorded the softening behavior of a cantilever pipe beam during the deformation process due to individual sections exceeding the critical curvature
Based on the moment-curvature relationship obtained by four-point bending experiments for the empty pipe and the large deflection governing equation based on a generalized constitutive equation, Reid et al [5] used a 2D model of in-plane deformation and a 3D model including out-of-plane deformation to numerically simulate the elastic-plastic dynamic response of a cantilevered empty pipe

Summary

Introduction

Pipes for conveying high-energy and high-pressure fluids are widely used in nuclear power plants and petrochemical facilities. For the air- lled case, an internal pressure of 15 MPa can increase the peak bending moment and critical curvature from 262 N·m and 1.25 m−1 in an empty pipe to 343 N·m and 2.7 m−1.

Results

Conclusion