http://yetl.yabesh.ir/yetl1/handle/yetl/19046 Tue, 25 Aug 2026 19:14:10 GMT 2026-08-25T19:14:10Z https://localhost:443/yetl1/bitstream/id/184256/ http://yetl.yabesh.ir/yetl1/handle/yetl/19046 http://yetl.yabesh.ir/yetl1/handle/yetl/4316937 Experimental Verification of Spherical Worm Wheel Dressing and Internal Helical Gear Grinding Based on the Virtual Center Distance Method Wei, Peng; Wang, Huiliang; Su, Jianxin Abstract. The grinding principle of a spherical worm wheel is used to determine the coordinate system for the tooth surface of an equivalent helical gear that envelops the worm wheel. The equation for the tooth surface is reverse-engineered to construct a model. The dressing principle for the grinding wheel based on the virtual center distance method is used to examine the motion structure of the gear grinding machine and dressing motion characteristics of the grinding wheel. A coordinate system for the diamond roller dressing of the spherical worm grinding wheel is established. The four-axis linkage of the machine tool enables the grinding wheel to undergo deflection, thereby completing the dressing cycle. The grinding process is simulated, and theoretical predictions are experimentally validated. The results confirm the accuracy of the internal helical gear with the worm wheel, and this demonstrates the rationality and effectiveness of the proposed dressing approach. Overall, this study presents significant advancements in the field of gear manufacturing and provides valuable insights for future developments in grinding technology. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316937 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316926 Modeling of Surface Roughness and Material Removal in Fixed-Abrasive Lapping of Optical Glass Considering Dynamic Profile Baseline Jia, Yufan; Zhu, Xianglong; Wang, Xuefei; Cai, Yindi; Kang, Renke; Gao, Shang; Yang, Lei Abstract. Fixed-abrasive lapping has been widely applied in the precision machining of hard and brittle materials. Its well-controlled abrasive motion and dominant two-body removal mechanism enable superior surface quality. However, due to multiple process parameters and the complex removal mechanism, surface quality control still relies heavily on empirical knowledge. To improve the controllability of the lapping process, this study proposes a two-dimensional microscale surface profile simulation model that incorporates pad topography, material removal mechanisms, and microscale contact characteristics. The model innovatively introduces dynamic profile baseline updating, abrasive scratching angle, and elastic recovery. Experiments were conducted on fused quartz under different lapping forces and lapping plate rotational speeds. The close agreement between the simulated and experimental results validates the model's effectiveness in predicting surface profile, surface roughness, and material removal rate. Furthermore, surface roughness analysis was used to optimize both lapping force and plate speed. This work provides new insights into the microscale evolution of surface profiles in fixed-abrasive lapping and offers a theoretical basis for process parameter optimization. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316926 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316921 A Study on Microstructure Evolution, High Temperature Deformation, and Fracture Characteristics of Wire Arc Additively Manufactured Inconel 625 Alloy Kishor, Gaurav; Mugada, Krishna Kishore; Mahto, Raju Prasad; Sivanandam, Aravindan; Digavalli, Ravi Kumar; Amirthalingam, Murugaiyan Abstract. The present research focuses on the hot deformation behavior, microstructure, texture evolution, and fracture mechanisms of wire arc additively manufactured Inconel 625 alloy. The deposited material exhibits columnar, cellular, and dendritic grain structures, with grain widths ranging between 10 μm and 40 μm and lengths extending up to 150 μm. The deformation characteristics were studied across a temperature range of 700–900 °C. At medium temperatures, distinct serrations were observed, transitioning from B type to C type as the temperature increased. At elevated temperatures, B-type serrations reappeared, attributed to interactions between C14-Ni2Nb Laves phases and mobile dislocations, as revealed by transmission electron microscopy (TEM) analysis. Conversely, C-type serrations were associated with the nucleation and growth of deformation twins. Grain size and boundaries under varying deformation temperatures were examined using electron backscattered diffraction (EBSD) and TEM, which revealed the occurrence of dynamic recrystallization (DRX). It was observed that the preferred orientation for DRX nucleation in the Inconel 625 alloy is along the ⟨001⟩ direction. At 900 °C, recrystallized grains were prominent, with EBSD results confirming both discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX), where CDRX acted as a secondary nucleation mechanism. Below 900 °C, cracks primarily nucleate due to stress concentrations near Nb-rich phases. At 900 °C, crack initiation was influenced by slip band impingement at grain boundaries combined with stress concentrations around Nb-rich phases. Furthermore, void formation at grain boundary triple junctions caused by grain boundary sliding contributed to ductile fracture. The high-temperature deformation behavior of wire arc additive manufacturing-deposited Inconel 625 is strongly influenced by the interplay of DDRX and CDRX mechanisms. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316921 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316914 Tailoring Thermal and Mechanical Performance Through Multimaterial Laser Powder Directed Energy Deposition of Copper and 17-4PH Stainless Steel Heinrich, Lauren; Hoffmann, Miguel; Herberger, Callan; Kannan, Rangasayee; Nandwana, Peeyush; Fillingim, Kenton B.; Saldaña, Christopher; Feldhausen, Thomas Abstract. This study investigates the additive manufacturing (AM) processing, microstructural evolution, and resulting mechanical and thermal properties of multimaterial components combining 17-4PH stainless steel and pure copper (Cu) fabricated via laser powder directed energy deposition (LP-DED). Conventional tooling steels exhibit limited thermal conductivity, significantly constraining production throughput in high-volume processes. Incorporating Cu, with its superior thermal conductivity, could significantly enhance tool performance, though Cu and steel present metallurgical incompatibilities when processed via AM. A systematic investigation was conducted across compositions ranging from 0 to 100 wt% Cu, revealing critical thresholds influencing solidification behavior, defect formation, microstructure, hardness, and thermal transport. Optical microscopy, electron backscatter diffraction (EBSD), hardness testing, and thermal conductivity measurements provided comprehensive process–structure–property correlations. Severe hot cracking occurred at low-Cu contents (6–25 wt%), aligning generally well with crack susceptibility modeling, with an unexpected discrepancy at 25 wt%. Porosity remained low (≥99% dense) throughout the compositional spectrum. EBSD analysis revealed a transformation from columnar martensitic structures at low-Cu contents to equiaxed FCC Cu-dominated structures at higher Cu concentrations, highlighting the complex microstructural transitions driven by Cu-induced changes in solidification and phase stability. Hardness decreased from 330 HV (pure 17-4PH) to 62 HV (pure Cu), consistent with microstructural changes. Concurrently, thermal conductivity improved substantially from 13.5 W/m K to 367.9 W/m K, emphasizing Cu’s dominant role in thermal transport. The findings highlight the feasibility of leveraging compositional gradients between 17-4PH and Cu to achieve tailored tooling with optimized thermal and mechanical performance. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316914 2026-01-01T00:00:00Z