15620

1583 دكتري

دكتري

ساخت و توليد

اصفهان : دانشگاه صنعتي اصفهان

1399

شانزده، 172ص.: مصور، جدول، نمودار

محسن بدرسماي، احسان فروزمهر

محمدرضا توكلي، مهدي كاروان

مهدي احمدي نجف آبادي، احمد كرمانپور، محمود فرزين، پيمان مصدق

1399/04/17

كتابنامه

مكانيك

مهندسي مكانيك

1399/04/17

2620917

166Assessment of Mechanical Characteristics of Parts Produced by Selective Laser Sintering Method with the aid of Controlling Thermal Regime inside the Building Platform Ali Kiani a kiani@me iut ac ir Date of Submission 2020 06 07 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree PhD Language FarsiMohsen Badrossamay mohsen badrossamay@cc iut ac ir 1st Supervisor Ehsan Foroozmehr eforoozmehr@cc iut ac ir 2nd Supervisor Mohammadreza Tavakoli mrtavak@cc iut ac ir Advisor Mehdi Karevan mkarevan@cc iut ac ir Advisor Assistant professor Department of mechanical Engineering Isfahan University of Technology Associated professor Department of mechanical Engineering Isfahan University of TechnologyAbstractThermal history is a key factor affecting mechanical properties of polymeric parts made by the selective lasersintering SLS process In this research the effect of thermal history on the mechanical properties of PA12parts produced by the SLS process has been investigated It is hypothesized that different cool down methods built orientations and scanning pattern could be influencing factors on the thermal history during the SLSprocess It was found that the built orientation was more effective than the cooling methods on ultimate tensilestrength UTS and elongation at break EaB so that UTS and EaB of the edgewise parts were 10 50 greater than the flat parts However the applied slowest cool down method slightly increased the edgewiseparts crystallinity to 23 compared to 19 2 for the normal cooled down samples In addition the impactresistance of parts was measured by the Izod impact test The results represented that changing the scanningpattern in normal cooling mode impressed the impact properties However the long cooling method decreasedthe differences of impact resistance in the various scanning patterns Additionally changing the builtorientation of the samples from the edgewise to flat position resulted in a decrease of the impact strength indiverse cooling methods The DSC analysis and SEM images outcomes were utilized to describe the obtainedresults Keywords Selective laser sintering PA12 Mechanical properties Thermal history CrystallinestructureIntroduction It has been seen that the thermal history of parts inside the machine has a great influence ontheir mechanical properties Some process parameters including energy density consistinglaser power and speed scan spacing and layer thickness preheating powder bedtemperature and scan strategy could affect the thermal history experienced by the partsduring the SLS Childs and Tontowi Childs and Tontowi 2001 studied the effects ofpreheating temperature and part built position in the powder bed on the density of PA12 SLSparts They suggested the empirical method to avoid part density reduction is to increaselaser energy density Starr et al Starr et al 2011 investigated the effects of energy densityparameters including laser power and speed scan spacing and layer thickness on themechanical properties of PA12 parts They showed that mechanical performance is

محسن بدرسماي، احسان فروزمهر

محمدرضا توكلي، مهدي كاروان

مهدي احمدي نجف آبادي، احمد كرمانپور، محمود فرزين، پيمان مصدق