Helical and slotted cylinder springs are indispensable elements in mechanical engineering. This paper investigates helical and slotted cylinder springs subjected to axial loads under static and dynamic conditions. The objective is to determine the stiffness of a circular cross-section helical coil compression spring and slotted cylinder springs with five sizes and dynamic characteristics. A theoretical and finite element models are developed and presented in order to describe the various steps undertaken to calculate the spring's stiffnesses. Five cases of the spring's geometric are presented. A finite element model was generated using ANSYS software and the stiffness matrix evaluated by applying a load along the spring's axis, then calculating the corresponding changes in deformation. The stiffness is obtained by solving the changes of load and deformation. The natural frequencies, mode shapes and transient response of springs are also determined. Finally, a comparison of the stiffnesses are obtained using the theoretical methods and those obtained from the finite element analysis were made and good agreement are evident and it can be found that the stiffness of spring for the slotted cylinder spring is much larger than that for helical spring and the stiffness for slotted cylinder spring increases with the number of slots per section. Natural frequencies, mode shape and transient response of helical spring and slotted cylinder spring have been represented in ANSYS software and results have been compared and it found that the natural frequency has also increased in the same proportion of stiffness because the natural frequency is directly proportional to the stiffness for all the cases that have been studied.

The influence of pack carburizing by different leftover organic materials was studied.Egg shell, dropping flower,orang shell mixed with charcoal, was used as refresher and its effect on corrosion fatigue of low carbon steel 1020 AISI (American Iron and Steel Institute) was studied. Carbon steel 1020 originally used for manufacturenumerousdevice parts such as gears, shaft, connecting rod.Severalsamples for the tensile and fatigueexaminationsareequipped from the based metalagreeing toASTM (American Society for Testing and Materials)descriptions. Pack carburizing is carried outby charcoal for liberation atomic carbon.The diffusion procedure on selectedsamples were pack carburizing using charcoal with addition leftover organic materialsas energies withratio of30% pack carburizing and at925 for two hours. After that, the samples quenched in water and tempered. Tensile,hardness, microstructures examination were implemented. Corrosion fatigue wascarried by rotating bending device in sea water 3.5% NaCl. The results showed that all carburizing compound causes an improving in corrosion fatigue due to the change in microstructure between the surface of specimens,its core and the comparative residual stress which produce by carburizing process.Egg shell give the high value and charcoal the lower value with respect to the basemetal.

In this paper, a cold multi-pass extrusion process for a 15mm in diameter solid 2024-T3 aluminum alloy rod was carried out using three dies to obtain three different diameters of 14mm, 13mm, and 12mm. The microstructure, hardness, and corrosion behavior were investigated before and after the extrusion process. Load-Displacement data were recorded during each extrusion process. The electrochemical corrosion test was made in a 3.5 wt.% NaCl solution using potentiostat instrument under static potentials test. Corrosion current was recorded to determine the corrosion rate for specimens. The results showed that the extrusion load increased with the number of extrusion passes, which is also seen in hardness test results. In addition, the corrosion rate decreased with the increase in the number of extrusion passes. This is due to severe plastic deformation, which generates a fine grain structure of (AlCu) and (AlCuMg) components.

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