Wyniki wyszukiwania - BazTech

1

A comparison of axial fatigue strength of coarse and ultrafine grain commercially pure titanium produced by ECAP

Naseri R., Hiradfar H., Shariati M., Kadkhodayan M.

Archives of Civil and Mechanical Engineering

|

2018

|

Vol. 18, no. 3

755--767

EN

Commercially pure titanium (CP-Ti) has been recently used as metallic biomaterials due to excellent biocompatibility and specific strength. CP-Ti has less static and dynamic strength as compared to other metallic biomaterials. Processing by the equal channel angular pressing (ECAP) as one of the most effective severe plastic deformation (SPD) method could lead to an increase in the mechanical strength of materials, significantly. In this study, Grade 2 CP-Ti billet is inserted into Al-7075 casing, and is then deformed by ECAP, with the channel angle of 135°, through 3 passes at route BC and room temperature. The purpose of using casing is to attain higher deformation homogeneity and more material ductility in the billet. The microstructural analysis shows that the coarse grain (CG) CP-Ti is developed to ultra-fine grain (UFG) structures after ECAP. In order to investigate the static and dynamic strength of CG and UFG CP-Ti, the tensile and axial fatigue tests are conducted. The results represent that UFG CP-Ti has much more tensile and fatigue strength than CG CP-Ti, and it could be utilized as biomaterials for production of implants. Surface features of fatigue fracture are also investigated. It should be noted that the investigation of fatigue strength of UFG CP-Ti produced by ECAP at RT utilizing casing, has not been conducted so far.

2

Numerical simulation of forming titanium thin-wall panels with stiffeners

Adamus Janina, Winowiecka Julita, Dyner Marcin, Lacki Piotr

Advances in Science and Technology. Research Journal

|

2018

|

Vol. 12, no 1

54--62

EN

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.

3

Analysis of forming thin titanium panels with stiffeners

Adamus J., Winowiecka J., Dyner M.

Archives of Metallurgy and Materials

|

2017

|

Vol. 62, iss. 1

173--180

EN

The growing demand for light and durable products has caused an increase in interest in products formed of thin sheets. In order to ensure sufficient stiffness of the drawn - parts, stiffening is often performed. Unfortunately, during the forming of stiffeners unwanted deformations of the drawn parts very often appear, which prevent them from further exploitation. In the paper, forming thin titanium panels with stiffeners is analysed. The panels are made of sheets of commercially pure titanium: Grades 2, 3 and 4. In the results of numerical analyses which were performed using PamStamp 2G, taking into consideration the impact of the blank holder force and friction conditions on the strain distribution in the drawn parts, sheet thinning and springback values are presented. The numerical analysis results were compared with the experimental tests. It was concluded that in order to prevent panel deformation being a result of residual stresses, it is necessary to ensure adequate friction conditions on the contact surfaces between the deformed material and tools as well as a suitable blank holder force.

4

Prediction of Shrinkage Porosity in Femoral Stem of Titanium Investment Casting

Sutiyoko, Suyitno, Mahardika M., Syamsudin A.

Archives of Foundry Engineering

|

2016

|

Vol. 16, iss. 4

157--162

EN

Design of gating system is an important factor in obtaining defect-free casting. One of the casting defects is a porosity caused by internal shrinkage in solidification process. Prediction of the internal shrinkage porosity in the femoral stem of commercially pure titanium (CP-Ti) is investigated based on the gating system design. The objective of this research is to get the best gating system between three gating system designs. Three gating system designs of the femoral stem were simulated in an investment casting method. The internal shrinkage porosity occurs on the largest part and near the ingate of the femoral stem. The gating system design that has ingates cross section area: 78.5; 157; and 128.5 mm2 has the least of the internal shrinkage porosity. This design has the most uniform solidification in the entire of the femoral stem. An experiment is conducted to validate the simulation data. The results of internal shrinkage porosity in the three gating system designs in the simulation were compared with the experiment. Based on the comparison, the trend of internal shrinkage porosity at the three gating system designs in the simulation agrees with the experiment. The results of this study will aid in the elimination of casting defect.