An accurate determination method for constitutive model of anisotropic tubular materials with DIC-based controlled biaxial tensile test

Positive displacement motors are widely used underground power tools in oil and gas extraction. In order to solve the problems of the short life of the conventional positive displacement motor and ...

External high-pressure forming of metal spiral tube of equal wall thickness:

/pdf/comparative-analysis-of-cold-and-warm-rolling-on-tensile-5b03o513.pdf

Comparative analysis of cold and warm rolling on tensile properties and microstructure of additive manufactured Inconel 718

Hydroforming patch technology for damaged screen pipes is designed based on tube hydroforming technology, and the methods for determining the forming pressure range and forming defects are selected according to the forming process. The hydroforming patch model for screen pipes is established according to the technical demand parameters for screen pipe repair. From the mechanical properties of the material and digital–analog comparison analysis of the material formability, it is found that the determiners for formability (such as forming pressure, thinning rate, and springback) of 321 stainless steel (SS321) are better than those of 304L stainless steel (SS304L), and the patch tube materials meeting the technical requirements were selected. A test bench for the formability of patch tubes was built to verify the forming pressure of patch tubes with different thicknesses and the distribution of wall thickness after forming. The results show that the hydroforming patch technology is feasible and can realize the firm and close fit between the patch tube and screen pipe; moreover, SS321 can meet the material requirements of the patch tube.

Analysis and experimental study of patch tube mechanical properties based on screen pipe hydroforming patch technology

Dual-pressure tube hydroforming (THF) is a tube-forming process that involves applying fluid pressure to a tube’s inner and outer surfaces to achieve deformation. This study investigates the effect of dual-pressure loading paths on material formability and tribological conditions. Specifically, pear-shaped and triangular cross-sectional parts were formed using dual-pressure modes where fluid pressure on the inside of the tubular blank was alternated with pressure on the outside surface of the tubular blank, causing the tube to expand/stretch and contract. During expansion, the tube conformed to the die’s cavity, while during contraction, the contact area between the die and the workpiece reduced, leading to decreased friction stress at the tube–die interface. Additionally, the reversal of pressure loadings caused the tubular blank to buckle, altering the stress state and potentially increasing local shear stress, improving material formability. Dual-pressure THF has demonstrated that the pressure loading paths chosen can substantially influence material formability. Comparing the geometries of parts formed by dual-pressure THF and conventional THF shows a significant increase in the protrusion height of both the pear-shaped and triangular specimens using dual-pressure THF.

/pdf/improving-material-formability-and-tribological-conditions-g8m5ok5t.pdf

Shi-Jian Yuan

Papers

Effects of superimposed hydrostatic pressure on bulging deformation and fracture of tubes in double-sided hydroforming

Analysis of thickness variation and stress state in hydroforming of complex T-shaped tubular part of nickel-based superalloy