Nowadays most of reciprocating compressors have one - way valves that act by difference pressure between behind and front of valves. In this article, experimental and numerical studying of one - way valves in reciprocating compressors was done. In this experimental tests, one – way valve with two different materials for rings; stainless steel with the material number 1.5022 and sign 38si6, and carbon-peek composite, were used. Numerical simulation for one-way valves with identical characteristics of experimental tests was done by CFX 5.7.1 and Ansys workbench 9.1. Experimental tests showed that life of carbon-peek composite ring was more than stainless steel. The most important cause of failure in the stainless steel ring was inappropriate distribution of forces due to the springs below the ring. Another common cause of failure in these valves was the stresses on walls in the location of springs that approved by numerical simulation. Difference in reaction of one - way valves in opening and closeing was another cause of failure because they were different in thermal expansion coefficient, thickness and diameter of carbon-peek composite and stainless steel rings. Appropriate thickness of rings determined by flow equation. The results obtained from numerical simulations have a good agreement with experimental tests. Manuscript profile

For making rivet and bolt connections, making a hole is necessary. While basic S-N graph can be extracted from design documents, analysis of stress can be used for two different approaches. The first approach is the theoretical derivation of analytical relations with simplified assumptions like planar stress or uniform bolt load distribution. The other one is the numerical simulation using robust codes like Abaqus software. By using these two approaches, residual stress distribution around the hole can be extracted in various conditions. In this experiment, an aluminium 2024-T3 plate with 3.2 mm thickness is considered. The stress analysis results and basic S-N graph were combined and discursive S-N graphs were obtained for different cold-expanded bolted holes. These graphs were compared with experimental data in several steps. First, the bolt fastening was considered. In the second step, cold expansion was considered and in the final step, the effects of fastening bolts and nuts and cold expansion was considered simultaneously. At last, a comparison between various steps was drawn. The results of this study showed that this new analytical method on distribution of residual stresses around cold expansion holes is as effectiveness as old methods. Manuscript profile

In this paper, a large-scale experimental study has been conducted in order to evaluate the high-velocity compaction of aluminum powder using Gas Detonation Forming (GDF) processing technique. In this series of experiments, the effect of the distribution of grain particle size, initial powder mass, and loading conditions on green density and strength of compacted products were thoroughly studied. The maximum relative green density and green strength of 97.6% and 17.9% were achieved. Group Method of Data Handling (GMDH)-type neural network in conjunction with Singular Value Decomposition (SVD) method was exerted to model the high-velocity compaction process of aluminum powder. The main objective of this idea is to demonstrate how two characteristics of the high-velocity compaction, namely, the relative green density and strength of products vary with the changing of significant parameters, involved in GDF processing technique. Manuscript profile