Dry friction depends on the surface topography which, in turn, is governed by machining parameters in addition to several other factors,. Therefore, in order to establish a qualitative relationship among these factors, the surface roughness and coefficient of static friction are measured for specimens machined on lathe and shaper machines with different values of machining parameters. For the case of lathe, the measured Ra value is found to increase with increase in feed rate and depth of cut, whereas, a marginal decrease is observed with increasing spindle speed. Similar results with respect to cutting speed have been obtained for the case of shaper machine. On the other hand, the coefficient of static friction, measured on steel substrate using inclined plane method, is found to decrease with increasing Ra values for both the specimen types.
Fracture parameters of a bi-material plate containing a cener crack and subjected to biaxial tensile loading was calculated numerically. Based on the crack tip stress field obtained numerically in a bi-material joint and using the finite element over deterministic (FEOD) method, the stress intensity factors (KI and KII) and also non-singular T-stress terms, were determined for different material properties and biaxial loading cases. Due to asymmetry of loading and material properties in the investigated dissimilar plate, the center crack experinces mixed mode I/II fracture in general. By increasing the bi-material constant value, which shows the difference between the mechanical properties of two materials, the amplitude of stress intensity factor decreases. The obtained results from this method were in good agreement with the displacment field method prevousiuly reported by other researchers.
In the present experimental study, two dissimilar sister aluminum alloys, 5083 and 5086, are welded through friction stir welding process. Different experiments are conducted on vertical milling machine through a fixture design and firm holding welding plates on it. These experiments are performed by varying welding parameters including welding speed, rpm, different pin profiles, tool tilt angle at five levels each. Two different mechanical properties of the welded specimen (i.e. tensile strength and percentage of elongation) have been tested and compared with the base metals to find out the joint efficiency. Also it is observed that rpm, tool tilt angle and different pin profiles make significant impacts on friction stir welded joints. Tool rpm increases the tensile strength to an extent. Also, tool pin profile affects the stirring or plastic flow of material under tool shoulder. It is shown through visual and optical analysis that surface finish and weld quality of joints depend on tool tilt angle.
The article is concerned with the research of the processes of formation of the structure and properties of systemically alloyed low carbon steel 10H3G3MF in initially hardened and initially cold-deformed condition at high speed thermal-cycle processing (TCP). Metallographic, dilatometric and fractographic analysis, transmission electronic microscopy and uniaxial tensile test and impact test (salt spray chamber) are used as the research methods. It is shown that the maximum fine crushing of grain structure of austenite to 1 micron with high speed TCP of the researched steel in initially cold-deformed condition occurs at the first cycle of heating to 900 ° C, at the same time nanostructural condition of martensite is realized with an average size of stick in the plane of the foil of 60 ± 10 nm, which results in a substantial increase of complex of mechanical properties. It was found that in all studied modes of high speed TCP the ? ? ?-conversion with heating in the inter-critical temperature range consists of three stages.
Various methods are available to reinforce concrete members and structures. Wrapping the concrete beams with composite sheets is one of the suggested methods for increasing the load bearing capacity of concrete beams and specially those containing opening. In this paper, the influence of using two composite sheets reinforced with carbon (CFRP) and glass (GFRP) is studied on increasing the strength of concrete beams having opening. A number of concrete beams with and without openings were modeled in ANSYS and using the nonlinear analyses, the initial cracking load, ultimate failure load, cracking pattern and deflection were determined numerically for each beam. Different wrapping schemes were examined for increasing the load bearing capacity of the opening section and it was concluded that wrapping from both inside and exterior of opening with the mentioned composite patches provide the most enhancement in the opening zone. Also the CFRP patch showed better performance in comparison with the GFRP wrapping.
This work illustrates the manufacturing of the honeycomb hexagonal topology structures by the kirigami technical, and the compressive testing of this specimen. The cellular configuration is simulated using a series of finite element models representing fullscale. The models are benchmarked against experimental results from pure compression tests. Finite element models of the honeycomb assemblies under compressive loading have been developed using nonlinear shell elements from an ANSYS code. Good agreement is observed between numerical nonlinear simulations and the experimental results.
This paper outlines the vibrational response of a cracked rotor in static and rotating condition through Campbell diagram. An open crack in the rotor changes its stiffness. The effect of which is seen on the natural frequency of the system. The natural frequency of the cracked rotor increases in comparison to un-cracked rotor. Experimental and simulation work is performed in the static condition to study the natural frequency of the rotor. Campbell diagram is generated through Simulation in ANSYS to study the critical speed variation at first (I) and second (II) Engine order (EO) line for cracked and un-cracked rotor.