Sharif Digital Repository

The purpose of this study was to investigate the main causes of the co-fracture of sixteen connecting bolts of a filter press cylinder-piston system. Stress state of the bolts during the service conditions has been analyzed and the failure reasons were determined from the fractography analysis and gathered information. According to the obtained results, it was concluded that the bolts had failed by the fatigue mechanism. It seems that insufficient torque was used during assembly  

First stage nozzles are considered as one of the most critical components in the heavy-duty gas turbines because of their operational in-service condition in the hot gas path. In the present research, the failure analysis of a first stage nozzle in a 159 MW gas turbine is investigated in order to specify the modes and mechanisms of the failure and their root causes. Various examinations including macroscopic and visual inspection of the nozzle outer surface, the micro examination of the fracture surface, chemical analysis and metallographic analysis were carried out to complete the investigation. The micro and macro examinations revealed cracks, erosion and oxidation damages in the nozzle... 

In this research, the possibility of producing asphalt mixtures containing Reclaimed Asphalt Pavement (RAP) that perform well from both fatigue and rutting points of view was studied. For this, seven asphalt mixtures with varying RAP percentage and total binder content were produced. All other variables, including the gradation and binder type, were kept constant. To better control for the production variables, the mixtures were produced in the laboratory. Fatigue and rutting properties of the mixtures were evaluated using the Simplified Viscoelastic Continuum Damage (S-VECD) model and Triaxial Stress Sweep (TSS) test, respectively. Next, FlexPAVETM software was utilized to predict the... 

Due to environmental concerns traditional eutectic tin-lead solder is gradually being replaced in electronic assemblies by "lead-free" solders. During this transition, nanoparticle technology is also being investigated to see whether improvements in joint reliability for high temperature applications can be made. Nanoparticles can be used to harden the solder via Zener pinning of the grain boundaries and reduce fatigue failure. This paper explores the effects of adding Silica nanoparticles to SnAgCu solder, and how the mechanical properties induced in the solder vary with temperature. It is found that above 100°C the mechanical response and microstructure of the normal and nanoparticle...