Modeling of Friction Phenomena of Ti-6Al-4V Sheets Based on Backward Elimination Regression and Multi-Layer Artificial Neural Networks

Abstract

This paper presents the application of multi-layer artificial neural networks (ANNs) and backward elimination regression for the prediction of values of the coefficient of friction (COF) of Ti-6Al-4V titanium alloy sheets. The results of the strip drawing test were used as data for the training networks. The strip drawing test was carried out under conditions of variable load and variable friction. Selected types of synthetic oils and environmentally friendly bio-degradable lubricants were used in the tests. ANN models were conducted for different network architectures and training methods: the quasi-Newton, Levenberg-Marquardt and back propagation. The values of root mean square (RMS) error and determination coefficient were adopted as evaluation criteria for ANNs. The minimum value of the RMS error for the training set (RMS = 0.0982) and the validation set (RMS = 0.1493) with the highest value of correlation coefficient (R2 = 0.91) was observed for a multi-layer network with eight neurons in the hidden layer trained using the quasi-Newton algorithm. As a result of the non-linear relationship between clamping and friction force, the value of the COF decreased with increasing load. The regression model F-value of 22.13 implies that the model with R2 = 0.6975 is significant. There is only a 0.01% chance that an F-value this large could occur due to noise.

Mechanical Properties and Residual Stress Measurements of Grade IV Titanium and Ti-6Al-4V and Ti-13Nb-13Zr Titanium Alloys after Laser Treatment

“…It is a two-phase alloy, characterized by a low density and very good corrosion resistance. It also shows good machinability and good mechanical properties, especially high mechanical strength in relation to its density [ 15 , 16 , 17 ]. However, recent research proves that the main elements contained in the Ti-6Al-4V alloy also have negative impacts on the human body.…”

Deformation Behavior of Wrought and EBAM Ti-6Al-4V under Scratch Testing

“…Actually, as can be seen from Figure 5, recovery of the scratch groove in the EBAM sample (41%) is even smaller than in the wrought sample (43%). According to the above proposed model, this can be attributed to the reverse α →α phase transformation resulting in volume shrinkage in the scratch groove, which could be induced by tensile stresses behind the moving indenter due to the high value of the coefficient of friction [40].…”

Single-Point Incremental Forming of Titanium and Titanium Alloy Sheets

“…The unfavorable phenomena accompanying the SPIF and TPIF of titanium alloys can be limited by appropriate surface treatment of the tools and the use of appropriately selected technological lubricants [ 141 , 142 ]. Due to the fact that most of the lubricants used in sheet metal forming (SMF) processes belong to the group of synthetic oils, in recent years research has been conducted on replacing mineral oils with biodegradable vegetable oils [ 143 , 144 ], including those with the addition of nanopowders [ 145 , 146 , 147 ]. Trzepieciński et al [ 144 ] tested the tribological properties of Ti-6Al-4V titanium alloy sheets in a strip drawing test using five kinds of vegetable oils: palm oil, rapeseed oil, olive oil, sunflower oil and soybean oil.…”

“…Due to the fact that most of the lubricants used in sheet metal forming (SMF) processes belong to the group of synthetic oils, in recent years research has been conducted on replacing mineral oils with biodegradable vegetable oils [ 143 , 144 ], including those with the addition of nanopowders [ 145 , 146 , 147 ]. Trzepieciński et al [ 144 ] tested the tribological properties of Ti-6Al-4V titanium alloy sheets in a strip drawing test using five kinds of vegetable oils: palm oil, rapeseed oil, olive oil, sunflower oil and soybean oil. It was found that increasing the load at a constant value of kinematic viscosity of lubricant reduces the value of the coefficient of friction (COF).…”