Engineering topics

Reza E Rabby, MD

Publications and source records attributed to Reza E Rabby, MD.

5 records

DOE OSTI2024

Impact of Backing Plate and Thermal Boundary Conditions for High-Speed Friction Stir Welding of 25-mm Thick Aluminum Alloy 7175-T79

Here this study demonstrates high-speed (150 mm/min) single pass friction stir butt joining of 25 mm thick aluminum alloy 7175-T79. To understand the impact of quenching and cooling rate on process responses, joint strength, and grain size distributions across the weld thickness, we performed a series of friction stir welding (FSW) trials in air and with a trailing water spray using steel and composite backing plates (BP). Welds made in air and trailing water spray exhibit significantly different hardness distributions across the nugget, heat affected zone (HAZ), and HAZ minimum hardness as evidenced by detailed microhardness mapping. The effect of trailing water spray (TWS) on joint efficiency overshadows the influence of BP composition due to the vastly different contribution to quenching. TWS also resulted in a multifaceted effect on FSW such as lowering processing temperature, increasing X and Z forces while lowering Y force, and narrow heat affecting zone. Finally, digital image correlation (DIC)-based fracture mode analysis and grain size measurements correlate with the hardness distribution.

42 ENGINEERING↗

DOE OSTI2024

Meshfree Process Modeling and Experimental Validation of Friction Riveting of Aluminum 5052 to Aluminum 6061

Friction riveting (Fric-riveting) is an innovative, fast, and energy-efficient process for spot-joining metal-metal structures. Although fric-riveting has been studied experimentally in recent years, its process modeling is rarely found in the literature primarily because of the associated large material deformation, extreme thermomechanical conditions, and complex contact conditions. In this work, a mesh-free smoothed particle hydrodynamics (SPH) framework that can well handle the abovementioned numerical challenges is used to simulate the fric-riveting of AA5052 to AA6061. Predicted material morphology, multi-point temperatures, and plunge force are thoroughly validated by experimental observations. The material severe plastic deformation zone in the vicinity of the riveting zone is further predicted by the SPH model, which indicates the material mixing and potential grain refinement zone. Based on the validated model, process parameters can be optimized which yields better performance over the baseline case.

Friction riveting (fric-riveting), Smoothed partic↗

DOE OSTI2023

Embedded anchoring of multi-material assemblies by friction riveting process

In this paper, we report on work that focused on extending the capability and broaden the applicability of the friction-riveting process for joining stacks composed of a wide range of multi-layer polymer-to-metals and similar and dissimilar metals. We first present direct experimental evidence of our use of this process to join aluminum-to-steel dissimilar metals with steel rivets. We have demonstrated for the first time the use of magnesium as a rivet material for joining carbon fiber reinforced polymer (CFRP) stacks, aluminum as a rivet material to laminate magnesium to CFRP, and aluminum-to-aluminum similar metal joining and aluminum-to-steel dissimilar metal joining with steel rivets. Our work sheds light on detailed process parameter optimization and the corresponding process response behavior, thus advancing our understanding of this complex joining method for a wide range of material combinations.

Friction-riveting, magnesium rivet, carbon fiber r↗

DOE OSTI2023

High speed butt joining of 1” thick 2139-T8

Thick plate (=1”) butt joining of Al alloys is challenging due to high tool forces, uneven material flow, and heat distribution in the through-thickness direction. Tool design and welding parameters used for executing thick plate butt joining have remained mostly static over the past decade. Reported welding speeds that produce viable joint strength (mostly on 6xxx alloys) typically range below 100 mm/min (4inches /min). Researchers at Pacific Northwest National Laboratory (PNNL) in association with Ground Vehicle Systems Center (US Army GVSC) have been working to demonstrate greater joining efficiency at higher welding speeds in a 1” thick AA2139-T8 plate. Using innovative tool features and effective force and temperature control a joint efficiency of 80% was demonstrated at a welding speed of 7 inches /min (178mm/min).

Das, Hrishikesh↗

DOE OSTI2023

Shear Assisted Processing and Extrusion of Unhomogenized Aluminum Alloy 6063 Castings with High Iron Content

Shear Assisted Processing and Extrusion (ShAPE) was used to fabricate aluminum 6063 tubing directly from secondary scrap. Trimmings from an automotive manufacturing facility were cast into billets spiked with iron (0.3 wt% Fe) to explore the tolerance of ShAPE to Fe contamination. Billets were extruded in the unhomogenized condition to form tubing with an outer diameter of 12 mm and wall thickness of 2 mm. Tensile properties reached 0.2% YS = 206 MPa, UTS = 238 MPa, and U.E. = 16.3% in the T6 temper. Performance exceeds the ASTM minimum standard and is on par with ASM typical values for conventional extrusion of primary aluminum billets in the fully homogenized condition. Microstructural characterization shows extensive refinement of grain size along with dispersion and refinement of Fe-Al-Si intermetallic phases. This study suggests that ShAPE extrusion may offer a lower carbon manufacturing pathway through direct recycling of secondary aluminum scrap and elimination of the billet homogenization step.

solid phase processing, AA 6063, extrusion, Shear ↗