فهرست مقالات exhaust manifold

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  1 - Improving High Cycle Fatigue Life in An Exhaust Manifold Using Perimeter Fins with Considering Stress Gradient
  Hojjat Ashouri
  10.30486/admt.2023.1977279.1396
  The effect of perimeter fins on the thermal stress and High Cycle Fatigue (HCF) life in an exhaust manifold with considering stress gradient was investigated. For this purpose, coupled thermo-mechanical analysis of an exhaust manifold was carried out. Then HCF life of t چکیده کامل

  The effect of perimeter fins on the thermal stress and High Cycle Fatigue (HCF) life in an exhaust manifold with considering stress gradient was investigated. For this purpose, coupled thermo-mechanical analysis of an exhaust manifold was carried out. Then HCF life of the component was predicted using a standard stress-life analysis and results were compared to the original exhaust manifold. Mechanical properties of exhaust manifold material were obtained by tensile tests at different temperature. The results of the thermo-mechanical analysis proved that the maximum temperature and stress are visible in the confluence region. The obtained Finite Element Analysis (FEA) proved the fact that perimeter fins reduce the temperature distribution in the exhaust manifolds about 31°C. As a result, the exhaust manifolds tolerate lower temperature and fatigue life will increase. The results of FEA indicated that the stress in the modified exhaust manifolds decreased approximately 19MPa for the sake of depletion of temperature gradient, which can lead to higher fatigue lifetime. The results of HCF showed that the number of cycles of failure for modified exhaust manifold is approximately 63% higher than the results obtained from the original exhaust manifolds. The results of the FEA analysis are compared with the real sample of the cracked exhaust manifold to properly evaluate the results, and it has been shown that critical identified areas correspond to the failure areas of the real sample. پرونده مقاله
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  2 - تحلیل خستگی چندمحوره منیفولد دود با درنظر گرفتن تنش ویسکوزیته
  حجت عاشوری
  منیفولد دود به علت هندسه پیچیده و شرایط بارگذاری يکی از چالش برانگیزترين قطعات موتور است. این قطعه باید نوسانات سیکلی تنش های ترمومکانیکی را در طول عمر خود تحمل کند. بنابراین شبیه سازی و تحلیل ترک های خستگی آن لازم و ضروری است. در این پژوهش، تحلیل عمر خستگی کم چرخه منیف چکیده کامل

  منیفولد دود به علت هندسه پیچیده و شرایط بارگذاری يکی از چالش برانگیزترين قطعات موتور است. این قطعه باید نوسانات سیکلی تنش های ترمومکانیکی را در طول عمر خود تحمل کند. بنابراین شبیه سازی و تحلیل ترک های خستگی آن لازم و ضروری است. در این پژوهش، تحلیل عمر خستگی کم چرخه منیفولد دود با استفاده از روش اجزای محدود و نرم افزار آباکوس به منظور پیش بینی دما و تنش و سپس عمر خستگی با استفاده از معیار چندمحوره صفحه بحرانی براون-میلر و نرم افزار MSC-FATIGUE انجام شده است. از ترکیب الگوی سخت شوندگی غیرخطی همگن-سینماتیک چابوچه با قانون تنش ویسکوز به منظور درنظر گرفتن اثر تنش ویسکوزیته استفاده شده است. نتایج تحلیل ترمومکانیکی نشان داد که بیشینه دما و تنش وان-مایسز 7/757 درجه سانتی¬گراد و 2/395 مگاپاسکال است و موقعیت آن در ناحیه همریختگاه است. پس همریختگاه منیفولد دود موتور ناحیه بحرانی است و احتمال ایجاد ترک های خستگی در آن وجود دارد. عمر خستگی منیفولد دود بدون و با در نظرگرفتن اثر تنش ویسکوزیته به ترتیب 9310 و 8850 سیکل محاسبه گردید. به عبارت دیگر درنظر نگرفتن اثر تنش ویسکوزیته در تحلیل عمر خستگی باعث می شود که تعداد سیکل های گسیختگی 460 سیکل یا حدود 2/5 درصد بیشتر از میزان مجاز تخمین زده شود. بنابراین لازم است اثر تنش ویسکوزیته در تحلیل عمر خستگی منیفولد دود درنظر گرفته شود. براي بررسي صحت نتايج تحلیل ترمومکانیکی و عمر خستگی، نتايج شبيه سازي شده با نمونه واقعي منیولد دود آسيب ديده مقايسه گردید و نشان داده شد که نواحي بحراني، مطابقت مناسبی با نواحي گسیختگی در نمونه واقعي دارد. پرونده مقاله
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  3 - Thermo-mechanical fatigue simulation of exhaust manifolds
  Hojat Ashori
  Loading conditions and complex geometry have led the exhaust manifolds heads to become the most challenging parts of diesel engines. Thermal fatigue failure of the engine components easily happens due to excessive temperature gradient and thermal stress. Modern exhaust چکیده کامل

  Loading conditions and complex geometry have led the exhaust manifolds heads to become the most challenging parts of diesel engines. Thermal fatigue failure of the engine components easily happens due to excessive temperature gradient and thermal stress. Modern exhaust systems must withstand severe cyclic mechanical and thermal loads throughout the whole life cycle. This study focuses on the Thermo-mechanical Fatigue (TMF) analysis for exhaust manifolds. The three-dimensional model of the exhaust manifolds was simulated in abaqus software and a chaboche model was utilized to investigate the elastic and plastic behavior of the exhaust manifolds. The numerical results showed that the temperature and thermal stresses have the most critical values at the confluence region of the exhaust manifolds. This area was under the cyclic tensile and compressive stress and then is under low cycle fatigue. After several cycles the fatigue cracks will appear in this region.The lifetime of this part can be determined through finite element analysis instead of experimental tests. پرونده مقاله
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  4 - Evaluation of Thermal Barrier Coating in Low Cycle Fatigue Life for Exhaust Manifold
  Hojjat Ashouri
  This paper presents low cycle fatigue (LCF) life prediction of a coated and uncoated exhaust manifolds. First Solidworks software was used to model the exhaust manifolds. A thermal barrier coating system was applied on the tubes c of the exhaust manifolds, consists of t چکیده کامل

  This paper presents low cycle fatigue (LCF) life prediction of a coated and uncoated exhaust manifolds. First Solidworks software was used to model the exhaust manifolds. A thermal barrier coating system was applied on the tubes c of the exhaust manifolds, consists of two-layer systems: a ceramic top coat (TC), made of yttria stabilized zirconia (YSZ), ZrO2-8%Y2O3 and also a metallic bond coat (BC), made of NiCrAlY. The temperature-dependent of material parameters was considered in order to increase the accuracy of LCF life results. Then Ansys Workbench software was used to determine stress and fatigue life based on Morrow and Smith-Watson-Topper (SWT) approaches. Thermal fatigue failure of the engine components easily happens due to excessive temperature gradient and thermal stress. Modern exhaust systems must withstand severe cyclic mechanical and thermal loads throughout the whole life cycle. The results of finite element analysis (FEA) showed that the thermal barrier coating system reduces the temperature about 29°C because of its lower thermal conductivity. As a result, the exhaust manifolds tolerates lower temperature and fatigue life will increase. The results of thermo-mechanical analysis indicated that the stress in the coated exhaust manifolds decreased approximately 25 MPa for the sake of depletion of temperature gradient which can lead to higher fatigue lifetime. The results of LCF proved that the number of cycles of failure for coated exhaust manifold is approximately in the order 2-fold longer, than the results obtained from the uncoated exhaust manifolds. پرونده مقاله
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  5 - Effect of residual stress in low cycle fatigue for coated exhaust manifold
  Hojjat ashouri
  The exhaust manifolds are subjected to higher loads than before, due to the increasing power output, fuel consumption and exhaust gas emission. Thus, simulation and analysis of fatigue cracks is essential. The effect of residual stress on the thermal stress and low cycl چکیده کامل

  The exhaust manifolds are subjected to higher loads than before, due to the increasing power output, fuel consumption and exhaust gas emission. Thus, simulation and analysis of fatigue cracks is essential. The effect of residual stress on the thermal stress and low cycle fatigue (LCF) life of exhaust manifolds using strain life methods was investigated. For this purpose, Solidworks software was used to model the exhaust manifolds. Then the thermo-mechanical analysis was carried out to determine the temperature and stress distribution in ANSYS software. Finally, the fatigue life prediction that considers residual stress effect was done. The simulated results proved that the thermal stresses and number of cycles to failure have the most critical values at the confluence region of the exhaust manifolds. The LCF results showed that the number of failure cycles for coated exhaust manifold is about 89% higher than the results obtained from the uncoated exhaust manifolds. Evaluating the residual stress, the TBC improves the number of failure cycles approximately 52% in comparison the uncoated exhaust manifold. The results of FEA proved a very good agreement between numerical simulation results and LCF analysis results, performed in references. پرونده مقاله