Comparative thermal buckling analysis of functionally graded plate

A thermal buckling analysis of functionally graded thick rectangular plates according to von Karman non-linear theory is presented. The material properties of the functionally graded plate, except for the Poisson's ratio, were assumed to be graded in the thickness direction, according to a power-law distribution, in terms of the volume fractions of the metal and ceramic constituents. Formulations of equilibrium and stability equations are derived using the high order shear deformation theory based on different types of shape functions. Analytical method for determination of the critical buckling temperature for uniform increase of temperature, linear and non-linear change of temperature across thickness of a plate is developed. Numerical results were obtained in MATLAB software using combinations of symbolic and numeric values. The paper presents comparative results of critical buckling temperature for different types of shape functions. The accuracy of the formulation presented is verified by comparing to results available from the literature

Shear strength testing of hardfaced samples using special tool on an universal testing machine

Complex working conditions of forging dies are the most frequent causes of their damage, requiring suitable hard facing repair procedures. The method of determining the bond strength between the hardfaced layer and the base material is explained in details, and the relation between hardfaced layer output results and the applied technology is established. Shear testing of materials has proven to be one of the most difficult areas of mechanical property testing. Shear modulus measurements are mainly accurate, but it is very difficult to measure shear strength. Edges, material coupling, non-pure shear loading, non-linear behaviour, imperfect stress distribution and coupling with normal stresses make shear strength determination difficult. None of the available test methods are without inaccuracies. Therefore, in structural applications, shear strength data should be used very carefully, on a case-by-case basis, appreciating the consequences of potential inaccuracies of the used values

Shear strength testing of hardfaced samples using special tool on an universal testing machine

Complex working conditions of forging dies are the most frequent causes of their damage, requiring suitable hard facing repair procedures. The method of determining the bond strength between the hardfaced layer and the base material is explained in details, and the relation between hardfaced layer output results and the applied technology is established. Shear testing of materials has proven to be one of the most difficult areas of mechanical property testing. Shear modulus measurements are mainly accurate, but it is very difficult to measure shear strength. Edges, material coupling, non-pure shear loading, non-linear behaviour, imperfect stress distribution and coupling with normal stresses make shear strength determination difficult. None of the available test methods are without inaccuracies. Therefore, in structural applications, shear strength data should be used very carefully, on a case-by-case basis, appreciating the consequences of potential inaccuracies of the used values

Determination of bond strength between the hard-faced (HF) layer and the base material (BM) of forging dies

This paper points out complex working conditions of forging dies, which are the most frequent causes of their damage, and proposes suitable hard-facing repair procedures. The shear strength between the hard-faced layer and base metal has been measured using specially developed tool, and correlation between output results and the applied hard-facing technology is established

Reparation of the damaged forging hammer mallet by hard facing and weld cladding

In this paper the problems related to the maintenance of large forging mallets of pneumatic hammers including hard facing of cracked or worn working surfaces are considered. Actually, the choice of optimum technology for the reparation of hard facing of the broken forging press frame and cracked mallet of the forging pneumatic hammer are taken into consideration

Reparation of the damaged forging hammer mallet by hard facing and weld cladding

In this paper the problems related to the maintenance of large forging mallets of pneumatic hammers including hard facing of cracked or worn working surfaces are considered. Actually, the choice of optimum technology for the reparation of hard facing of the broken forging press frame and cracked mallet of the forging pneumatic hammer are taken into consideration

Selection of the most appropriate welding technology for hardfacing of bucket teeth

A possibility of extending the service life of the working parts of construction machinery with particular attention to hardfacing of loader bucket teeth was investigated. In the first part of this paper the tribological processes typical for this machinery is analysed. Worn excavator parts are made of conditionally weldable cast steel that requires a special hardfacing technology, so numerous investigations were performed to obtain the most appropriate technology. In the experimental part of the paper, the selection of the optimum hardfacing technology for bucket teeth and the procedure of the manual arc hardfacing are presented. The samples were first hardfaced using different techniques and technologies and then the microstructure and microhardness of characteristic hardfaced layers were studied. Specially prepared samples were used for tribological investigations. The results of experimental investigations enabled the selection of the most suitable hardfacing technology and its application to real parts. The bucket teeth, with their hardfaced layers applied vertically, horizontally or in a honeycomb pattern were mounted onto a loader bucket, alternated with the new non-hardfaced teeth and their performance during the operation was regularly monitored. After a certain period, the degrees of the wear for the non-hardfaced and differently hardfaced teeth were measured. Taking into account both technical and economic factors, the most suitable hardfacing technology was determined

Selection of the most appropriate welding technology for hardfacing of bucket teeth

A possibility of extending the service life of the working parts of construction machinery with particular attention to hardfacing of loader bucket teeth was investigated. In the first part of this paper the tribological processes typical for this machinery is analysed. Worn excavator parts are made of conditionally weldable cast steel that requires a special hardfacing technology, so numerous investigations were performed to obtain the most appropriate technology. In the experimental part of the paper, the selection of the optimum hardfacing technology for bucket teeth and the procedure of the manual arc hardfacing are presented. The samples were first hardfaced using different techniques and technologies and then the microstructure and microhardness of characteristic hardfaced layers were studied. Specially prepared samples were used for tribological investigations. The results of experimental investigations enabled the selection of the most suitable hardfacing technology and its application to real parts. The bucket teeth, with their hardfaced layers applied vertically, horizontally or in a honeycomb pattern were mounted onto a loader bucket, alternated with the new non-hardfaced teeth and their performance during the operation was regularly monitored. After a certain period, the degrees of the wear for the non-hardfaced and differently hardfaced teeth were measured. Taking into account both technical and economic factors, the most suitable hardfacing technology was determined

Energetic analysis of hard facing and weld cladding of an air powered drop hammer damaged ram

This paper studies problems of hard facing of damaged and initially cracked mechanical engineering heavy parts of complex geometry such as large rams of air powered drop hammers. During long-term exploitation, these parts are subjected to thermal fatigue due to cyclic temperature changes and variable impact compression. Taking into consideration high ram costs and difficulties to purchase ram, the necessity of its reparation becomes obvious. The choices of the most suitable technologies of hard facing and welding of an initially cracked ram are also studied here. Besides the techno-economic analysis, an energetic analysis is performed as an additional criterion in assessment of the proposed technology

Estimates of weldability and selection of the optimal procedure and technology for welding of high strength steels

High strength steels belong into a group of high quality steels, with exceptional mechanical properties, especially in regards to tensile strength. At the same time, as their deficiency is emphasized the limited and difficult weldability. In other words, some of those steels are weldable only with application of special measures related to controlled heat input. In that way, the favorable mechanical properties can be kept within the heat affected zone, with condition that the optimal welding technology is selected. Existing, very scarce and often unclear and insufficient recommendations for selection of the optimal welding technology are one of the causes of large number of flaws in welded joints. Mentioned problems, as well as others, can be successfully solved by proper selection of the procedure, filler metal and technology of welding, verified by experiments conducted in laboratory or in real operating conditions. Those experiments can not be performed in arbitrary conditions. Thus, partially due to results reported in this paper, technologists will obtain the possibility to predict in advance, in a very short time period, the mechanical and metallurgical properties of joints of this class of high strength steels. This will be possible without conducting the large number of practical tests or relying on personal experience of a designer