Browsing by Subject "Ultrasonic Consolidation"
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Item Dislocation Density Based Finite Element Modeling of Ultrasonic Consolidation(University of Texas at Austin, 2010-09-23) Pal, D.; Stucker, B.E.A dislocation density based constitutive model has been developed and implemented into a crystal plasticity quasi‐static finite element framework. This approach captures the statistical evolution of dislocation structures and grain fragmentation at the bonding interface when sufficient boundary conditions pertaining to the Ultrasonic Consolidation process are prescribed. Hardening is incorporated using statistically stored and geometrically necessary dislocation densities (SSDs and GNDs), which are dislocation analogs of isotropic and kinematic hardening respectively. The GND considers strain‐gradient and thus renders the model size‐dependent. The model is calibrated using experimental data from published refereed literature and then validated for the Aluminum 3003 alloy.Item Dislocation Density Crystal Plasticity Based Finite Element Modeling of Ultrasonic Consolidation(University of Texas at Austin, 2011-08-17) Pal, D.; Stucker, B.E.A dislocation density based constitutive model has been developed and implemented into a crystal plasticity quasi-static finite element framework. This approach captures the statistical evolution of dislocation structures and grain fragmentation at the bonding interface when sufficient and necessary boundary conditions pertaining to the Ultrasonic Consolidation (UC) process are prescribed. The hardening is incorporated using statistically stored and geometrically necessary dislocation densities (SSDs and GNDs) which are dislocation analogs of isotropic and kinematic hardening respectively. Since, the macroscopic boundary conditions during UC involves cyclic sinusoidal simple shear loading along with constant normal pressure, the cross slip mechanism has been included in the evolution equation for SSDs. The inclusion of cross slip promotes slip irreversibility, dislocation storage and, hence, cyclic hardening during the UC. The GND considers strain-gradient and thus renders the model size-dependent. The model is calibrated using experimental data from published refereed literature for simple shear deformation of single crystalline pure aluminum alloy and uniaxial tension of polycrystalline Aluminum 3003-H18 alloy. The model also considers the tension-compression asymmetry in case the model is applied for deformation processes in hexagonal close packed pure Titanium and its alloy counterparts which will be investigated further in our proposed research program. One of the significant macroscopic contributions from this model development is to successfully accommodate the elasto-plastic contact problem involved in UC. The model also incorporates various local and global effects such as friction, thermal softening, acoustic softening, surface texture of the sonotrode and initial mating surfaces and presence of oxide-scale at the mating surfaces which further contribute significantly specifically to the grain substructure evolution at the interface and to the anisotropic bulk deformation away from the interface during UC in general. The model results have been predicted for Al-3003 H-18 alloy undergoing UC. A good agreement between the experimental and simulated results has been observed for the evolution of linear weld density and anisotropic global strengths macroscopically. Similarly, microscopic observations such as embrittlement due to grain substructure evolution and broken oxide layer at the UC interface has been also demonstrated by the simulation.Item An Energy Dissipative Constitutive Model for Multi-Surface Interfaces at Weld Defect Sites in Ultrasonic Consolidation(University of Texas at Austin, 2013) Patil, Nachiket; Pal, Deepankar; Stucker, Brent E.A new finite element based constitutive model has been developed for quantification of energy dissipation due to friction and plastic deformation at the mating interface of two surfaces during the Ultrasonic Consolidation process. This work will include bridging the mesoscopic response of a dislocation density based crystal plasticity finite element framework at inter and intra-granular scales and a point at the macroscopic scale. This response will be used to develop an energy dissipative constitutive model for multi-surface interfaces at the macroscopic scale. The constitutive model will be used for quantification of energy consumed at lack of fusion and trapped oxide defects present in the build and the amount of energy input required to compensate for it. This numerical procedure will help in real time optimization of process parameters and closed loop control.Item Improving Linear Weld Density in Ultrasonically Consolidated Parts(2006-09-14) Ram, G. D. Janaki; Yang, Y.; George, J.; Robinson, C.; Stucker, B. E.Ultrasonic consolidation is a novel additive manufacturing process with immense potential for fabrication of complex shaped three-dimensional metallic objects from metal foils. The proportion of bonded area to unbonded area along the layer interface, termed linear weld density (LWD), is perhaps the most important quality attribute of ultrasonically consolidated parts. Part mechanical properties largely depend on LWD and a high level of LWD must be ensured in parts intended for load-bearing structural applications. It is therefore necessary to understand what factors influence LWD or defect formation and devise methods to enhance bond formation during ultrasonic consolidation. The current work examines these issues and proposes strategies to ensure near 100% LWD in ultrasonically consolidated aluminum alloy 3003 parts. The work elucidates the effects of various process parameters on LWD and a qualitative understanding of the effects of process parameters on bond formation during ultrasonic consolidation is presented. The beneficial effects of using elevated substrate temperatures and its implications on overall manufacturing flexibility are discussed. A preliminary understanding of defect morphologies and defect formation is presented, based on which a method (involving surface machining) for minimizing defect incidence during ultrasonic consolidation is proposed and demonstrated. Finally, trade-offs between part quality and build time are discussed.Item Integrating UC and FDM to Create a Support Materials Deposition System(University of Texas at Austin, 2009-09-15) Swank, M.L.; Strucker, B.E.; Medina, F.R.; Wicker, R.B.Currently there is no automated deposition system available for support materials in Ultrasonic Consolidation. Support materials are important to the UC technology because of the benefits that can be geometrically achieved. Without an integrated support materials system many geometries and features will be impossible to create. This paper describes the approach taken to integrate UC and FDM in order to automatically deposit materials as a support in a UC machine. This includes the process setup, design, and planning. Finally a build process integrating the two machines is shown to demonstrate that automated support material deposition in UC is possible.Item Integration of Direct-Write (DW) and Ultrasonic Consolidation (UC) Technologies to Create Advanced Structures with Embedded Electrical Circuitry(2006-09-14) Robinson, Christopher J.; Stucker, Brent; Lopes, Amit J.; Wicker, Ryan; Palmer, Jeremy A.In many instances conductive traces are needed in small, compact and enclosed areas. However, with traditional manufacturing techniques, embedded electrical traces or antenna arrays have not been a possibility. By integrating Direct Write and Ultrasonic Consolidation technologies, electronic circuitry, antennas and other devices can be manufactured directly into a solid metal structure and subsequently completely enclosed. This can achieve a significant reduction in mass and volume of a complex electronic system without compromising performance.Item Investigation of Support Materials for Use in Ultrasonic Consolidation(University of Texas at Austin, 2009-09-15) Swank, M.L.; Strucker, B.E.This paper provides an overview of the need for supports and what characterizes a good support material for Ultrasonic Consolidation. The goal is to look at a broad range of possible support material choices and the benefits and drawbacks of each. By manually depositing support materials during a build, each material is evaluated for its performance for three different configurations: an enclosed pocket, freestanding rib, and open channel. These configurations represent commonly seen features that often need to be built using Ultrasonic Consolidation, but currently cannot be well constructed. The builds are constructed with 3003 Aluminum tapes at room temperature. Microstructures are also studied to evaluate the consolidated material.Item Maximum Height to Width Ratio of Freestanding Structures Built Using Ultrasonic Consolidation(2006-09-14) Robinson, C. J.; Zhang, C.; Janaki Ram, G. D.; Siggard, E. J.; Stucker, B.; Li, L.Ultrasonic consolidation (UC) is a process whereby metal foils can be metallurgically bonded at or near room temperature. The UC process works by inducing high-speed differential motion (~20kHz) between a newly deposited layer and a substrate (which consists of a base plate and any previously deposited layers of material). This differential motion causes plastic deformation at the interface, which breaks up surface oxides and deforms surface asperities, bringing clean metal surfaces into intimate contact, where bonding occurs. If the substrate is not stiff enough to resist deflection during ultrasonic excitation of newly deposited layers, then it deflects along with the newly deposited layer, resulting in no differential motion and lack of bonding. Geometric issues which control substrate stiffness and deflection were investigated at Utah State University by building a number of free-standing rib structures with varying dimensions and orientations. Each structure was built to a height where lack of bonding between the previously deposited layers and the newly deposited layer caused the building process to fail, a height to width ratio (H/W) of approximately 1:1. The parts were then cut, polished, and viewed under a microscope. An ANSYS model was created to investigate analytically the cause of this failure. It appears build failure is due to excessive deflection of the ribs around a 1:1 H/W, resulting in insufficient differential motion and deformation to achieve bonding. Preliminary results show, when the H/W reaches 1:1, the von Mises stress is found to be tensile along portions of the bonding interface, which eliminates the compressive frictional forces necessary for plastic deformation and formation of a metallurgical bond. These tensile stresses are shown to be concentrated at regions near the edges of the newly deposited foil layer.Item Process Parameters Optimization for Ultrasonically Consolidated Fiber-Reinforced Metal Matrix Composites(2006-09-14) Yang, Y.; Janaki Ram, G. D.; Stucker, B. E.As an emerging rapid prototyping technology, Ultrasonic Consolidation (UC) has been used to successfully fabricate metal matrix composites (MMC). The intent of this study is to identify the optimum combination of processing parameters, including oscillation amplitude, welding speed, normal force, operating temperature and fiber orientation, for manufacture of long fiber-reinforced MMCs. The experiments were designed using the Taguchi method, and an L25 orthogonal array was utilized to determine the influences of each parameter. SiC fibers of 0.1mm diameter were successfully embedded into an Al 3003 metal matrix. Two methods were employed to characterize the bonding between the fiber and matrix material: optical/electron microscopy and push-out tests monitored by an acoustic emission (AE) sensor. SEM images and data from push-out tests were analyzed and optimum combinations of parameters were achieved.Item Structurally Embedded Electrical Systems Using Ultrasonic Consolidation (UC)(2006) Siggard, Erik J.; Madhusoodanan, Anand S.; Stucker, Brent; Eames, BrandonCurrent research has demonstrated the use of Ultrasonic Consolidation (UC) to embed several USB-based sensors into aluminum, and is working toward embedding suites of sensors, heaters and other devices, connected via USB hubs, which can be monitored and controlled using an embedded USB capable processor. Additionally, the research has shown that electronics can be embedded at room temperature, but with some inter-layer delamination between the ultrasonically bonded aluminum layers. Embedding sensors and electronics at 300o F to overcome the delamination issues resulted in optimal bonding, and the sensors used thus far have functioned normally. Future investigation will explore other UC parameter combinations to ascertain the quality of embedding at lower temperatures.