Peter D. Lloyd

Thermographic In-Situ Process Monitoring of the Electron Beam Melting Technology used in Additive Manufacturing

Oak Ridge National Laboratory (ORNL) has been utilizing the ARCAM electron beam melting technology to additively manufacture complex geometric structures directly from powder. Although the technology has demonstrated the ability to decrease costs, decrease manufacturing lead-time and fabricate complex structures that are impossible to fabricate through conventional processing techniques, certification of the component quality can be challenging. Because the process involves the continuous deposition of successive layers of material, each layer can be examined without destructively testing the component. However, in-situ process monitoring is difficult due to metallization on inside surfaces caused by evaporation and condensation of metal from the melt pool. This work describes a solution to one of the challenges to continuously imaging inside of the chamber during the EBM process. Here, the utilization of a continuously moving Mylar film canister is described. Results will be presented related to in-situ process monitoring and how this technique results in improved mechanical properties and reliability of the process.

Structure and mechanical behavior of Big Area Additive Manufacturing (BAAM) materials

Purpose This paper aims to investigate the deposited structure and mechanical performance of printed materials obtained during initial development of the Big Area Additive Manufacturing (BAAM) system at Oak Ridge National Laboratory. Issues unique to large-scale polymer deposition are identified and presented to reduce the learning curve for the development of similar systems. Design/methodology/approach Although the BAAM’s individual extruded bead is 10-20× larger (∼9 mm) than the typical small-scale systems, the overall characteristics of the deposited material are very similar. This study relates the structure of BAAM materials to the material composition, deposition parameters and resulting mechanical performance. Findings Materials investigated during initial trials are suitable for stiffness-limited applications. The strength of printed materials can be significantly reduced by voids and imperfect fusion between layers. Deposited material was found to have voids between adjacent beads and micro-porosity within a given bead. Failure generally occurs at interfaces between adjacent beads and successive layers, indicating imperfect contact area and polymer fusion. Practical implications The incorporation of second-phase reinforcement in printed materials can significantly improve stiffness but can result in notable anisotropy that needs to be accounted for in the design of BAAM-printed structures. Originality/value This initial evaluation of BAAM-deposited structures and mechanical performance will guide the current research effort for improving interlaminar strength and process control.

Telerobotic planning and control for DOE D&D operations

The purpose of this paper is to describe the development of a telerobotic system focused on addressing the complex tasks found in real-world deactivation and decommissioning (D&D) activities for the Department of Energy. Because of the large gap between the conditions and constraints required to implement robotic systems and the conditions encountered in in situ D&D work, nearly all D&D activities that are too hazardous for direct human contact are presently executed using purely teleoperated remote systems. Advances in capability and efficiency can be achieved by developing new telerobotic control methodologies that integrate tasks ideally suited for robotic control with task definitions provided by more traditional teleoperated control. The objectives are to reduce task execution time, reduce the required operator skill level, and to enable the use of tools that are not suited for purely teleoperated control.

Calibrating IR cameras for in-situ temperature measurement during the electron beam melt processing of Inconel 718 and Ti-Al6-V4

High performance mid-wave infrared (IR) cameras are used for in-situ electron beam melt process monitoring and temperature measurements. Since standard factory calibrations are insufficient due to very low transmissions of the leaded glass window required for X-ray absorption, two techniques for temperature calibrations are compared. In-situ measurement of emittance will also be discussed. Ultimately, these imaging systems have the potential for routine use for online quality assurance and feedback control.

A Modular Telerobotic Architecture for Waste Retrieval and Remediation

The Oak Ridge National Laboratory (ORNL) has developed and de ployed a telerobotic approach for the remote retrieval of hazardous and radioactive wastes from underground storage tanks. The teler obotic system, built by SparAerospace Ltd., is capable of dislodging and removing sludge and gravel-like wastes without endangering the human operators through direct contact with the environment. Working in partnership with Washington University, ORNL is im plementing an event-based planner/Function-Based Sharing Con troller (FBSC) as an integral part of their overall telerobotic archi tecture. These aspects of the system enable the seamless union of the human operator and an autonomous controller in such a way as to emphasize safety without loss of performance. The cooperation between ORNL, Spar, and Washington University requires an open and modular control software architecture to enable the parallel de velopment of various components of the system. ControlShell has been used as the underlying software architecture to help meet these criteria of generality and modularity.

Force-based needle insertion for medical applications

Needle insertion is pervasive in almost all medical activities. The development of compact, lightweight automated tools for needle insertion with the reliability of an expert needle-inserting nurse could significantly reduce the risk to both civilian and military patients. Such tools could open the door to many advanced concepts for future medicine by being an “enabler” of one of the first actions in almost all procedures. The purpose of this paper is to discuss two force-based devices that address the needle insertion problem: a compliance-sensing system that mimics the nurse palpation to determine the best needle insertion point across a vein, and a needle insertion device that uses force-based profiles during insertion to achieve successful catheterization without puncturing the vein back wall. The methodologies and implementation approaches for the two enabling systems are described. Experimental data obtained with training pads and phantom arms are presented and discussed.

Design and Control of a Ship Motion Simulation Platform from an Energy Efficiency Perspective

Abstract Most hydraulic servo systems are designed with little consideration for energy efficiency. Pumps are selected based upon required peak power demands, valves are chosen primarily for their rated flow, actuators for the maximum force. However, the design of a hydraulic servo system has great potential in terms of energy efficiency that has, for the most part, been ignored. This paper describes the design and control of a large-scale ship motion simulation platform that was designed and built at Oak Ridge National Laboratory for the Office of Naval Research. The primary reasons to incorporate energy-efficiency features into the design are cost and size reduction. A preliminary survey of proposed designs based on traditional motion simulation platform configurations (Stewart Platforms) required hydraulic power supplies approaching 1.22 MW. This manuscript describes the combined design and control effort that led to a system with the same performance requirements, however requiring a primary power supply that was less than 100 kW. The objective of this paper is to illustrate alternative design and control approaches that can significantly reduce the power requirements of hydraulic systems and improve the overall energy-efficiency of large-scale hydraulically actuated systems.

Modular planning/control architecture for the semiautonomous control of telerobots in a hazardous environment

The Oak Ridge National Laboratory (ORNL) has demonstrated, evaluated, and deployed a telerobotic approach for the remote retrieval of hazardous and radioactive wastes from underground storage tanks. The telerobotic system, built by Spar Aerospace Ltd., is capable of dislodging and removing sludge and gravel- like wastes without endangering the human operators through contact with the environment. Working in partnership with Washington University, ORNL has implemented an Event based planner/function based sharing control (FBSC) as an integral part of their overall telerobotic architecture. These aspects of the system enable the seamless union of the human operator and an autonomous controller in such a way to emphasize safety without any loss of performance. The cooperation between ORNL, Spar, and Washington University requires an open and modular control software architecture to enable the parallel development of various components of the system. ControlShell has been used as the underlying software architecture to help meet these criteria of generality and modularity.