Polymeric materials are increasingly used in the automotive industry, aeronautics, medical device industry, etc. due to their advantage of providing good mechanical strength at low weight. The incremental forming process for polymeric materials is gaining increasing importance because of the advantages it offers: relatively complex parts can be produced at minimum cost without the need for complex and expensive dies. Knowing the main strains and especially the thickness reduction is particularly important as it directly contributes to the mechanical strength of the processed parts, including in operation. For the design of experiments, the Taguchi method was chosen, with an L₁₈ orthogonal array obtained by varying the material on two levels (polyamide and polyethylene) and the other three parameters on three levels: punch diameter (6 mm, 8 mm and 10 mm), wall angle (50°, 55° and 60°) and step down (0.5 mm, 0.75 mm and 1 mm). The output parameters were strain in the x direction, strain in the y direction, major strain, minor strain, shear angle and thickness reduction. Two analyses were conducted: signal-to-noise ratio analysis with the smaller-is-better condition and analysis of variance. The optimum values for which the thickness was reduced were the following: wall angle of 50°, punch diameter of 10 mm and step down of 0.75 mm.

The present paper focuses on analyzing the occurrence of defects such as dents and local deformations by laboratory simulations of a real case of a defect detected on a natural gas distribution pipeline lain at a depth of approximately 0.6 m. The defect is caused by a river stone which due to the compression forces, damages the pipe to the point of cracking. In the laboratory, the simulation was carried out on a steel pipe insulated with extruded polyethylene which was acted upon by a mandrel made of duralumin. The purpose of the tests is to determine the maximum values at which the pipe material fractures. It was found that the fracture of the pipes when there are rigid bodies in the protective layer of sand is accelerated by the sand existing between them and the pipe and by the change in the properties of the steel the pipes are made of when they are kept in water.

This paper describes the method of calculating the forces which appear at the bending of perforated plates with holes of different shapes and placed in different patterns, by means of a dynamometric table which uses resistive tensometric transducers (strain gauges). It also describes an instrument for the recording of data from the dynamometric table, a tool created with the aid of the “TestPoint” software which, beneath the data recording, ensures the filtering and statistic processing of data. The obtained results are displayed in comparative graphs for six types of perforated plates, as well as for an unperforated plate.

The present paper aims to study the behaviour of Metal Active Gas (MAG) tailor welded blanks during the single point incremental forming process (SPIF) from an experimental point of view. The single point incremental forming process was chosen for manufacturing truncated cone and truncated pyramid shaped parts. The same material (S355) and the same thickness (0.9 mm) were selected for the joining of blank sheets because the main goal of the paper was to study the influence of the MAG welding process throughout the SPIF process. A Kuka robot, equipped with a force transducer and an optical measurement system were used for manufacturing and evaluating the parts by SPIF. The selected output data were major and minor strain, thickness reduction, forces and springback at the SPIF process. Another line test was performed to evaluate the formability in SPIF. The main conclusion of the paper is that during the SPIF process, fractures occur in one side welded blanks even at moderate wall angles, while in the case of double side welded blanks there is a decrease of formability but parts can still be produced at moderate angles (55 degrees) without any problems.

This aim of this paper is to perform a study on the way the material of the fittings that can be welded through eletrofusion on polyethylene pipes withstands. The process is observed by means of the thermal and fast cameras. Also we intend to analyze the way the assembly consisting of the polyethylene fitting and pipe behaves during welding. The stresses caused by the welding process are observed, as well as the concurrent welding of the tapping tee and the branch saddle tee.

The aim of this paper is to identify the most suitable material model for the numerical simulation of the incremental forming of polymeric materials using the finite element method. The analysis program used was Ls-Dyna, and two material models, namely material 24 (Piecewise Linear Plasticity) and material 89 (Plasticity Polymer), were chosen for comparison from the library of the program. A comparison was made between two polymeric materials, polyamide PA 6.6 and polyethylene HDPE 1000, with the following dimensions of the forming tools: punch diameter, D_p = 6 mm; die length, L_d = 190 mm; die radius, R_d = 5 mm; die corner radius, R_corner = 10 mm; and blankholder length, L_bl = 190 mm. The simulation using the finite element method was performed with the Ls-Dyna software, and the experimental research was carried out using the Kuka KR210-2 robot. The strains were measured with the Aramis 2M optical system. Experimental investigations were carried out simultaneously, and the results obtained were compared in terms of main strains, thickness reduction, and forces on three directions. Close results were obtained between theoretical and experimental research for both material models.