The current study aims to evaluate the performance of the ultrasonic vibration-assisted milling (USVAM) process when machining two different materials with high deviations in mechanical properties, specifically 7075 aluminium alloy and Ti-6Al-4V titanium alloy. Additionally, this study seeks to develop an AI-based model to predict the process performance based on experimental data for the different workpiece characteristics. In this regard, an ultrasonic vibratory setup was designed to provide vibration oscillations at 28 kHz frequency and 8 µm amplitude in the cutting feed direction for the two characterised materials of 7075 aluminium alloy (150 BHN) and Ti-6Al-4V titanium alloy (350 BHN) workpieces. A series of slotting experiments were conducted using both conventional milling (CM) and USVAM techniques. The axial cutting force and machined slot surface roughness were evaluated for each method. Subsequently, Support Vector Regression (SVR) and artificial neural network (ANN) models were built, tested and compared. AI-based models were developed to analyse the experimental results and predict the process performance for both workpieces. The experiments demonstrated a significant reduction in cutting force by up to 30% and an improvement in surface roughness by approximately four times when using USVAM compared to CM for both materials. Validated by the experimental findings, the ANN model accurately and better predicted the performance metrics with RMSE = 0.11 µm and 0.12 N for Al surface roughness and cutting force. Regarding Ti, surface roughness and cutting force were predicted with RMSE of 0.12 µm and 0.14 N, respectively. The results indicate that USVAM significantly enhances milling performance in terms of a reduced cutting force and improved surface roughness for both 7075 aluminium alloy and Ti-6Al-4V titanium alloy. The ANN model proved to be an effective tool for predicting the outcomes of the USVAM process, offering valuable insights for optimising milling operations across different materials.

This study investigated the stress–strain behavior of seamless pipes in the hoop direction using the ring expansion test, which is a non-standardized mechanical testing technique used for evaluating the mechanical properties of round tubes. However, this technique has limitations, such as unidentified specimen geometry, strain measurement, and the estimation of friction coefficients. The study employed experimental, numerical, and analytical methodologies to address these limitations and throughout the study, a novel hoop stress correlation factor (K) was identified to be multiplied by the hoop stress derived equation for reduced section ring specimens. The experimental strain was measured using a newly derived analytical equation, and a mathematical predictive model was developed to estimate the K-factor using the Design of Experiment (DoE) and Design-Expert statistical software. The study concluded that the ring expansion test is a promising technique for evaluating the mechanical properties of seamless pipes similar to the unified axial tensile stress–strain behavior. However, future research is needed to estimate the hoop stress correlation value (K) for all ring geometries. The study's finding of the novel hoop stress correlation factor (K) in the case of a reduced section ring specimen is particularly noteworthy, as it addresses a significant research gap in the field.

This article presents a design development for the ring expansion test as an alternative technique of burst test to determine the mechanical properties of circular homogeneous thin-walled tubes in the hoop direction where it is supposed to fail. This is done by replacing the internal fluid pressure in burst test by a solid mandrel partitioned into an equal number of pieces. The numerical analyses were carried out using the commercial finite element method (FEM) package ABAQUS/CAE. The testing system consists of a multispecies mandrel assembled with two identical cones from top and bottom, and the ring specimen circumscribes the mandrel, which expands radially as a result of the cone’s axial displacement. The FEM was used to optimize the proposed design in terms of the minimum number of pieces in use. In addition, the effects of friction between the cones/the mandrel and between the ring/the mandrel are investigated. The FEM revealed that eight mandrel pieces or more are needed to preserve a uniform hoop stress throughout the ring circumference. Moreover, the FEM results in conjunction with theoretical formulas revealed that eight mandrel pieces at a minimum are required to minimize the power dissipated because of friction to a nuance value of 2 %. It is concluded that the higher the number of pieces used, the more uniform the hoop stress generated in the ring specimen. Moreover, it can effectively decrease friction effect at the ring/mandrel interface. The FEM also makes a great contribution in estimating the friction coefficients as it is restricted to be evaluated experimentally.

Background The ring expansion technique is a non-standardized material testing used to evaluate round tubes’ mechanical properties such as burst pressure and stress-strain behavior, however, this technique has limitations such as lack of suggested specimen geometry, strain measurement technique, and friction coefficient(s) estimation. Objective This study primarily aims to evaluate the stress-strain property in the hoop direction for seamless pipes with a further correlation with the tensile stress-strain curve. Moreover, investigating the specimen’s geometry effect on the results was also considered throughout the study. Methods Experimental, simulation, and analytical techniques were carried out and through their conjunction, it was applicable to estimate hard-to-measure coefficients, identify and evaluate new correction factors, and validate the simulation and analytical results. Results Experimental strain measurements were performed by derived analytical equation rather than an external measuring device, novel evaluation of the hoop stress correction value (K) was performed by the comparison between experimental and simulation work, in addition to a convenient similarity between the standard tensile test and the non-conventional proposed technique results. Conclusion The ring expansion test is a promising technique to evaluate the seamless pipes' burst pressure, stress-strain behavior, and other mechanical properties. Furthermore, the authors recommend future work regarding estimating both pressure dissipation factor (α) in terms of friction coefficients and hoop stress correction value (K) in terms of ring’s geometry.