Analytical expressions for stress distributions in lined pipes: Axial stress and contact pressure interaction

A Simplified Approach for the Hydro-Forming Process of Bi-Metallic Composite Pipe

“…Both physical and geometric nonlinearity is contained, in addition to the complex boundary conditions [1][2][3], which make it difficult to establish a rigorous theoretical analysis for hydraulic bulging and drawing forming of bi-metallic composite pipe. Some researchers employed finite element simulation to perform relevant analysis, good results were obtained [4][5][6]; In 1976, Krips once studied the process of tube expanding in a sheet for manufacturing heat exchanger [7,8], he proposed an analytical solution for residual contact pressure of such tube expanding in a sheet, his assumptions were an ideal elastic-plastic material model, and the same elastic modulus for both tube and sheet materials. While in 1982, Masashi Takemoto gave the relationship between the expanding pressure P i and the contact between the pressure P c by assuming Tresca yield criterion and ideal elastic-plastic material model [9].…”

New interpretations of gripping force tests for lined pipes

“…The error(s) introduced by the simplifying assumptions listed above have been shown by Vedeld et al [12] to have a negligible influence on the overall solutions relevant for this paper, since comparisons to full 3D solutions using a sophisticated finite element approach showed excellent correspondence to the derived equations. The coordinate system chosen in this paper is a standard cylindrical coordinate system, as depicted in Fig.…”

“…Moderate to significant underestimation of the residual hoop stresses will also be demonstrated. Based on the formulas deduced by Vedeld et al [12], it is shown that more reasonable interpretations, with less statistical deviations, are attained for available test results.…”

“…The governing equations which will be applied in this paper are deduced by Vedeld et al [12] and therefore the same underlying assumptions are introduced herein. For ease of reference, essential assumptions are listed:…”

“…This paper applies physical testing reported by Focke [4], as well as physical testing conducted by DNV, according to API 5LD [3], and re-interprets the tests based on formulas deduced by Vedeld et al [12]. It will be shown that the test interpretation regime recommended by API 5LD [3] results in significant underestimation of residual axial stresses and the Coulomb friction coefficient.…”