https://onlinelibrary.wiley.com/doi/pdf/10.1002/adem.202100437

Profilometry-Based Inverse Finite Element Method Indentation Plastometry

Investigation on the microstructural and mechanical properties of a Polytetrafluoroethylene thin film by radio frequency magnetron sputtering

Biaxial residual stress measurement by indentation energy difference method: Theoretical and experimental study

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adem.202001478

The Effect of Residual Stresses on Stress‐Strain Curves obtained via Profilometry‐based Inverse FEM Indentation Plastometry (PIP)

Residual stresses, existed in engineering structures, could significantly influence the mechanical properties of structures. Accurate and non-destructive evaluation of the non-equibiaxial residual stresses in these structures is of great value for predicting their mechanical performance. In this work, investigating the mechanical behaviors of instrumented spherical indentation on stressed samples revealed that non-equibiaxial residual stresses could shift the load-depth curve upwards or downwards and cause the residual indentation imprint to be an elliptical one. Through theoretical, experimental, and finite element (FE) analyses, two characteristic indentation parameters, i.e., the relative change in loading curvature and the asymmetry factor of the residual indentation imprint, were found to have optimal sensitivity to residual stresses at a depth of 0.01R (R is the radius of spherical indenter). With the aid of dimensional analysis and FE simulations, non-equibiaxial residual stresses were quantitatively correlated with these two characteristic indentation parameters. The spherical indentation method was then proposed to evaluate non-equibiaxial residual stress based on these two correlations. Applications were illustrated on metallic samples (AA 7075-T6 and AA 2014-T6) with various introduced stresses. Both the numerical and experimental verifications demonstrated that the proposed method could evaluate non-equibiaxial surface residual stresses with reasonable accuracy.

https://www.mdpi.com/2075-4701/10/4/440/pdf

Evaluation of Non-Equibiaxial Residual Stresses in Metallic Materials via Instrumented Spherical Indentation

A cost-effective voice coil motor-based portable micro-indentation device for in situ testing

Multiple acoustic source localization using deep data association

The invention provides a friction stir welding device with a double-sided circulation cooling effect. A circulation cooling plate is placed on a lower bottom plate, two pieces of welding materials areplaced on the circulation cooling plate and arranged on the circulation cooling plate in a mutually abutting mode, machining direction positioning is conducted on the welding materials through a lower positioning key of the lower bottom plate, and the welding materials are subjected to transverse positioning through upper positioning keys of upper pressing plates; the positioning keys can move inthe positioning direction and are fixed through screws; the two pieces of upper pressing plates are placed on the welding materials and arranged on the welding materials in a left-right symmetrical mode; a stirring area is contained between the two upper pressing plates, and a stirring head is arranged in the stirring area; and the circulation cooling plate is fixed into the lower bottom plate, upper cooling plates are clamped in the upper pressing plates, the upper parts of the upper cooling plates are filled with ice blocks, and after being molten, the ice blocks flow out from gaps betweenthe upper cooling plates and the upper pressing plates. The friction stir welding device can conduct double-sided cooling, direct contact with water is avoided, through design of a circulation structure, the utilization rate of cooling liquid is increased, and thus mechanical properties of the welding materials are improved.

Friction stir welding device with double-sided circulating cooling effect

A disposable puncture outfit with an effusion collecting cavity comprises a funnel-shaped puncture sleeve, a puncture needle, a connecting piece, an effusion collecting cavity and a sealing membrane,wherein the puncture needle is matched with the funnel-shaped puncture sleeve into a whole through the connecting piece, and the funnel-shaped puncture sleeve is provided with the effusion collectingcavity for collecting the backflow effusion; an air vent valve is arranged on the funnel-shaped puncture sleeve and used for introducing inert gas so as to bulge a certain space in the abdominal cavity to facilitate operation; the sealing film is embedded at an upper port of the funnel-shaped puncture sleeve, and an opening used for enabling the puncture needle and the surgical instrument to passthrough is formed in middle of the sealing membrane. The disposable puncture outfit avoids insufficiency of effusion backflow into the abdominal cavity when gauze that has absorbed the effusion is taken away from the trocar, thereby improving cleaning efficiency and saving operation time.

Chen Jianfeng

Papers

Evaluation of Non-Equibiaxial Residual Stresses in Metallic Materials via Instrumented Spherical Indentation

A cost-effective voice coil motor-based portable micro-indentation device for in situ testing

Multiple acoustic source localization using deep data association

Friction stir welding device with double-sided circulating cooling effect

Disposable puncture outfit with effusion collecting cavity