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Showing 3 results for Saeidi Googarchin

H. Saeidi Googarchin, S. M. Hossein Sharifi ,
Volume 5, Issue 1 (3-2015)

The reason of this study is low cycle failure of cast iron cylinder head during the E5 standard durability test. The goal of the present investigation is durability test simulation and low cycle fatigue life evaluation of cast iron cylinder head. With uncouple structural analysis, preloads, thermal and mechanical load and boundary conditions are prescribed to finite element model of the cylinder head. To cover the durability test, the analysis steps repeated at five crack speed, 750, 1650, 2075, 2350 and 2600 rpm. The cylinder head is subjected to cyclic multi-axial non-proportional variable amplitude loads. In fatigue analysis, critical plane model with cumulative damage theory is applied to predict fatigue life. A general scripting is developed and validated to calculate fatigue life. The results show that the failure of critical cylinder head is the type of low cycle fatigue. The valve bridge region, where high temperature exists during operation of the engine, is the critical area in cast iron cylinder head in fatigue analysis approach. The simulation results are in accordance with the results of durability test.
P. Shojaei Shahmirzadi, H. Saeidi Googarchin,
Volume 6, Issue 4 (12-2016)

Off-road cars’ windshields are vulnerable to different types of stones, road debris and pebbles due to common off paved and gravel surfaces in which they drive. Any attempt to design windshield that minimizes injury and death of occupants during a vehicle accident requires a thorough understanding of the mechanical behavior of automotive windshield subjected to foreign object impact loads.

In this study, some drop ball tests in different impact energy levels are conducted in order to monitor fracture behavior of an off-road automotive windshield. Also dynamic crack patterns of laminated glasses are examined based on the impact energy levels and impact conditions. In addition, the acceleration which is imposed to impactor during the accident is recorded. The experimental results are compared to an analytical approach regarding the resultant impact force as well. There is a good agreement between the impact forces of experimental test results and analytical approaches ones. All in all, in low velocity impacts, impact energy releases through powdering region in impact area, radial cracks and strain energy in PVB. It is concluded that in lower impact energy levels, the higher impact speed, the more number of radial cracks. In addition, at higher energy levels, number of radial cracks decease due to higher strain energy levels in PVB interlayer. Therefore, in low velocity impacts, number of radial cracks has reverse relationship with penetration depth in PVB interlayer.

Hamed Saeidi Googarchin, Ali Qasemian, Mohammad Rouhi Moghanlou,
Volume 10, Issue 4 (12-2020)

The primary objective of a brake disc is to absorb frictional heat during braking and dissipated it immediately by convection and radiation. However, during hard and repetitive brakings, thermal coning on brake disc generates surface hot spots which are responsible for the undesired accumulation of compressive stresses on the surface of the brake disc. These stresses would lead to disc cracking and finally failure of it. In the current paper, a coupled transient thermo-mechanical FE analysis of a heavy vehicle braking system is carried out in a way that thermal coning of the disc and surface hot spots and bands are recognizable. Braking condition is chosen from a standard for hard braking in trucks. Moreover, five additional braking actions with different severities are investigated to study the effects of braking severity on thermo-mechanical instability of brake discs. Comparison of numerical results of transient temperature during braking and cooling phases with experiment reveal a high accuracy of thermal prediction of this model. Also, the results show that thermal coning of brake disc is varied between 0.05 to 0.7 mm depending on braking severity and tangential location of the disc. Additionally, surface hot spots experience higher temperature gradients in higher decelerations. Finally, results show that circumferential compressive stresses during braking are the major component of thermal stresses and should be taken into account for life estimation analysis.

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