9794

9038

كارشناسي ارشد

ساخت و توليد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1393

چهارده، 98ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

احسان فروزمهر، محسن بدرسماي

محمدرضا فروزان

94/1/29

محمود كدخدايي، صالح اكبرزاده

1396/09/25

كتابنامه

مكانيك

مهندسي مكانيك

ID9038

چكيده خستگي يكي از مهمترين و شايعترين علل شكست در قطعات مكانيكي تحت بارگذار چرخها است و قطعاتي مانند پره توربين موتورها هوافضايي و يا پره كمپرسورها قطعاتياند كه قرباني اين فرآيند شكست هستند مهمترين روش برا بهبود عمر خستگي اينگونه قطعات ايجاد تنش پسماند فشار با روشها گوناگون است در اين پاياننامه فرآيند ليزر شاك پينينگ يا LSP با استفاده از دوسر تجهيزات ليزر پرانرژ و كم انرژ موردمطالعه تجربي قرارگرفته است به اين منظور نمونههايي از جنسها مس خالص و همچنين آلياژ آلومينيم 1606 6 T با استفاده از فرآيند LSP فرآور شده و مقدار تغيير شكل مسي و نيز شرايط سطحي مقدار تغييرات سختي نمونهها ريزساختار تنش پسماند و زبر نمونهها آلومينيمي بعد از بررسيها نشان داد كه فرآيند LSP فرآيند ارزيابيشده است ميتواند در نمونهها مسي تغيير شكل به شكل خمش ايجاد كند كه ميتوان از آن بهعنوان يك فرآيند خمكار فويلها استفاده كرد همچنين سختي و تنش پسماند فشار و زبر سطح نمونهها آلومينيمي را افزايش داده و موجب بروز ريزدانگي در آنها شود علاوه بر آن نتايج نشانداد كه در صورت رعايت نكردن

Experimental Study on Laser Shock Peening of Copper and Aluminium Alloys Arman Salimian arman salimian@me iut ac ir Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors Mohsen Badrossamay mohsen badrossamay@cc iut ac irEhsan Foroozmehr eforoozmehr@cc iut ac irAbstract In the past 30 years a new thechnology has emerged for improving surfacecompressive residual stress in order to positively influence fatigue behavior wearresistance Stress Crack Corosion S C C and Flying Object Damage FOD of advancedaerospace components This new thechnology is called Laser Shock Peening LSP Inthis process a high intensity short pulsed laser is used to generate an extreamly highpressure plasma plum to introduce compressive residual stress to the surface of thecomponents In this thesi this advanced surface modifying process is investigatedexperimentally At first the process is introduced and all factors and parameters affectingits impacts on process outputs are introduced accurately and then the process isinvestigated in two separate phases In the first phase of the experiments using an Nd YAG laser with 100mJ of energy per pulse and pulse width of 100 ns LSP wasconducted on foils of copper with 0 09 mm thickness Compressive residual stress causedby LSP would bend the foils and this bend is used as a measure for evaluating theprocess capabilities Studies showed this process could be beneficial to be used as anaccurate micro bending tool In the second phase using another Nd YAG laser withpulse energy of 1200 mJ and pulse width of 8 ns LSP process was conducted on Al 6061 T6 blocks and effect of process parameters including number of laser shots spot overlaprates and scan pattern on micro hardness in depth and surface roughness was studied Furthuemore microstructure of samples after LSP was studied Finally using XRDresidual stress measurement method residual stresses of processed and non processedsamples were measured The results showed that using the foregoing experimental setup deep and high amplitude compressive residual stress can be induced on the surface of Al6061 T6 samples On the other hand it was observed that the hardness of the samplescan be improved as a consequence of LSP Finally it was spotted that the surfaceroughness of samples processed by LSP can be deteriorated depending on the processparameters Key word Laser Shock Peening Residual Stress Bending of Thin Foils Al6061 T6 Hardness Roughness

احسان فروزمهر، محسن بدرسماي

محمدرضا فروزان

محمود كدخدايي، صالح اكبرزاده