Piotr Lacki

THE EFFECT OF HARDENING LAYERS AND TECHNOLOGICAL LUBRICANTS ON HEAT EXCHANGE BETWEEN WORKPIECE AND DIE

Abstract In this paper the numerical analysis of influence of contact force on the heat transfer in a forging process is presented. The contact force distribution obtained from the simulation of the forging process is used to analyse the heat transfer between the workpiece and the tool. Experimental results of the influence of contact force on the heat flux between two contact surfaces are shown. The numerical analysis has been performed using the ADINA system.

Numerical Simulation of Welding Thin Titanium Sheets

Different titanium grades are used in aircraft construction because of titaniums unique properties. These materials are mostly joined by different welding methods. Electron beam welding technology is often used in the aircraft industry to join structural elements made of titanium alloys. The goal of the work is a numerical analysis of the electron beam welding process applied to joining thin titanium sheets. The analysis was performed using finite element method, FEM. Temperature distribution, size of heat affected zone (HAZ), depth and width of fusion zone were determined for the assumed heat source model. Thermo-mechanical (TMC) simulation of the electron beam welding process using FEM is presented in the paper. The joining of two sheets, one made of commercially pure titanium Grade 2 and the other made of titanium alloy Grade 5 (Ti6Al4V), is analysed in the work. For the sheet welding process distributions of temperature, effective stress, and sheet deformation were calculated.

Possibility of the Increase in Titanium Sheets' Drawability

Forming of titanium sheets, especially titanium alloy sheets, is very difficult due to low drawability caused by a high ratio of the yield point to the tensile strength Re/Rm, usually more than 90%. Although drawability of titanium sheets can be enhanced by forming at elevated temperatures it is avoided due to the high costs and difficulties associated with the operation of the process. Therefore the authors have developed an unconventional stamping method allowing for forming of almost unworkable materials at ambient temperature, such as Ti6Al4V titanium alloy. The paper presents both numerical simulation and experimental results of the stamping process using a device specially designed for this purpose.

Numerical Simulation of Electron Beam Welding Process of Inconel 706 Sheets

Welding operation of aircraft engine sheet part will be analyzed in this paper. The sheet part is made of narrow Inconel 706 sheet pieces. During manufacturing process first sheets undergo the process of bending. Subsequently they are welded to produce the final shape. Finite element analysis will be used to model welding operation. The thermal field and its impact on the stress field will be analyzed. The produced results will be used to design the actual welding process. Sheets will be welded using electron beam welding, EBW, method. This method is characterized by high concentration of power which instantly melts metal. As a result small HAZ is produced and comparatively small distortions are introduced. EBW process is characterized mainly by three input parameters: beam voltage, beam current and welding speed. The goal of numerical simulation is to identify the values of input parameters that produce full-depth fusion zone. As a guideline for simulation the actual dependency between input parameters and weld pool geometry will be taken from calibration data for EB welding unit. Calibration was performed using 18-8 steel. Partial least square method will be used to project those data on Inconel 706 alloy.

Evaluation of Load-Bearing Capacity of Resistance Spot Welding (RSW) Joints Made of Titanium Gr 5 Sheets

The paper presents an analysis of load capacity for welded specimens made of titanium Grade 5 of 0.8 mm thickness. The lap joins were made by Resistance Spot Welding (RSW). The load capacity for joints with a single spot were assessed. The joints were welded with 5 variants of welding parameters. On the basis of the capacity of the joints, the best performance were selected. The best welding parameters were used to make three types of joints with different spacing of the welds: with a single weld, the two welds arranged parallel to the shearing direction and two welds arranged perpendicular to the shearing direction. The load capacity, a plastic strains distribution and a method of cracking were assessed. An example of the feasibility of a beam construction made of titanium grade 5 sheets welded by resistance spot welding were shown.

Analysis of Heat Transfer through PVC Window Profile Reinforced with Ti6Al4V Alloy

This requires the use of additional reinforcement in order to prevent excessive or permanent deformation of PVC windows. In the paper particular attention was devoted to space located in a corrosive environment exposed to chemical agents. For this purpose, proposed to change the previously used steel profiles reinforcements made of Ti6Al4V titanium alloy corrosion-resistant in the air, at sea and many types of industrial atmosphere. Analysis of the thermal insulation properties of PVC windows with additional reinforcement of profile Ti6Al4V titanium alloy was performed. PVC window set in a layer of thermal insulation was analyzed. Research was conducted using Finite Element Analysis. Numerical models and thermal calculations were made in the program ADINA, assuming appropriate material parameters. The constant internal temperature of 20 ̊ and an outer-20 ̊ was assumed. The course of temperature distribution in baffle in time 24 hours and graphs of characteristic points was obtained. The time of in which followed the steady flow of heat, as well as the course of isotherm of characteristic temperature in the baffle was determined. On the basis of numerical analysis obtained vector distribution of heat flux q [W/m2] and was determined heat transfer coefficients U [W/m2K] for the whole window with titanium reinforcement . All results were compared with the model of PVC windows reinforced with steel profile.

Modelling of Fine Blanking Process of the Aluminium Sheets

The required technological quality of the blanked products can be achieved through operations of fine blanking. This allows for obtaining products with improved dimensional accuracy and good quality cut-surface. In order to cut products from soft materials, including aluminium and its alloys, the methods of fine blanking with upsetting and fine blanking with reduced clearance are typically employed. The study presents the results of numerical modelling of the fine blanking process for a disk made of 1-millimetre sheet aluminium EN AW-1070A. The goal of the numerical simulations was to evaluate the effect of clearance between blanking die and the punch, and the impact of V-ring indenter on stress and strain distribution in the shearing zone.

Numerical Simulation of Forming Titanium Thin-wall Panels with Stiffeners

Due to the increase in the application of titanium components made of thin titanium sheets, in the work titanium panels made of 4 mm thick sheets are analysed. To increase the rigidity of the panels, some cross-shaped stiffeners were made. Such panels enable a reduction in weight while maintaining the existing strength of the drawn parts. Three kinds of commercially pure titanium are considered: Grade 1, 2 and 3. Numerical calculations were performed with PamStamp 2G based on the finite element method. The basic mechanical and technological properties of the analysed sheets, which are necessary for numerical modelling, were determined by static tensile testing. The friction coefficient was assumed based on the literature. On the basis of the performed numerical analyses, it was stated that the proper forming of panels with stiffeners depends not only on the drawability of the sheets but also on the technological parameters such as blank holder force and frictional conditions.

Numerical Analysis of Bridge Girder with Composite Dowel Shear Connection

Abstract The work presents a brief description of VFT-WIB® steel-concrete composite beams, examples of composite dowel shear connection shapes are presented. A steel-concrete bridge girder construction solution for the new shape of composite dowel shear connection was proposed. The geometric parameters of the steel section web cutting line are given. For the assumed cross-section dimensions, a numerical model of the girder was made. Numerical analysis was performed, the results of which were compared with the results of the analytical calculations. A program of actions aimed at further optimization of the model is presented.

Numerical Analysis of Prefabricated Steel-Concrete Composite Floor in Typical Lipsk Building

Abstract The aim of the work was to perform numerical analysis of a steel-concrete composite floor located in a LIPSK type building. A numerical model of the analytically designed floor was performed. The floor was in a six-storey, retail and service building. The thickness of a prefabricated slab was 100 mm. The two-row, crisscrossed reinforcement of the slab was made from φ16 mm rods with a spacing of 150 x 200 mm. The span of the beams made of steel IPE 160 profiles was 6.00 m and they were spaced every 1.20 m. The steelconcrete composite was obtained using 80×16 Nelson fasteners. The numerical analysis was carried out using the ADINA System based on the Finite Element Method. The stresses and strains in the steel and concrete elements, the distribution of the forces in the reinforcement bars and cracking in concrete were evaluated. The FEM model was made from 3D-solid finite elements (IPE profile and concrete slab) and truss elements (reinforcement bars). The adopted steel material model takes into consideration the plastic state, while the adopted concrete material model takes into account material cracks.