Assessing crack susceptibility in blended copper-stainless steel compositions during laser directed energy deposition-based additive manufacturing

This study investigates the effect of composition and process parameters on the crack susceptibility of the Cu -SS304L system during laser directed energy deposition (LDED). The microstructure of LDED deposits is analysed aiming at elemental distribution and crack susceptibility. The trapping behaviour of Cu changes with Cu concentration. The crack susceptibility reduces with Cu concentration and escalates with an increase in laser power and scan speed, irrespective of composition. The mode of solidification cracking varied from the rupture of Cu film to crack-assisted porosity. Furthermore, the critical solidification cooling rate is estimated for LDED of different blended Cu -SS for crack-free deposition. The above findings offer insights into cracking behaviour and provide processing guidelines for LDED of Cu -SS

Identifying optimum process strategy to build geometrically stable cylindrical wall structures using laser directed energy deposition based additive manufacturing

One of the bottlenecks for wider industrial acceptance of Laser Directed Energy Deposition (LDED) based additive manufacturing technique is the limited dimensional accuracy during the processing stage. This paper reports an investigation to identify the optimum process strategy to build dimensionally accurate and near-net-shaped cylindrical wall structures with minimum hump height. Four different approaches are deployed to identify the optimum process strategy by varying laser scan pattern (offset and spiral strategy), and speed ratio (SR) (dwell speed/scan speed) in an inert atmosphere of argon gas. An offset strategy with SR > 1 is found to be suitable for building near-net-shaped and stable cylindrical wall structures using LDED

Assessing crack susceptibility in blended copper-stainless steel compositions during laser directed energy deposition-based additive manufacturing

This study investigates the effect of composition and process parameters on the crack susceptibility of the Cu -SS304L system during laser directed energy deposition (LDED). The microstructure of LDED deposits is analysed aiming at elemental distribution and crack susceptibility. The trapping behaviour of Cu changes with Cu concentration. The crack susceptibility reduces with Cu concentration and escalates with an increase in laser power and scan speed, irrespective of composition. The mode of solidification cracking varied from the rupture of Cu film to crack-assisted porosity. Furthermore, the critical solidification cooling rate is estimated for LDED of different blended Cu -SS for crack-free deposition. The above findings offer insights into cracking behaviour and provide processing guidelines for LDED of Cu -SS

Changes in the French Defence Innovation System: New Roles and Capabilities for the Government Agency for Defence

Defence innovation systems are structured around two main groups of players that interact in the development of complex programmes: the state (the client and the government agency) and the systems integrators. Technological and institutional changes since the 1990s have affected the division of labour and knowledge in the industry. In this paper, we show the origins of these changes based on information derived from 45 qualitative interviews conducted between 2000 and 2008, which demonstrate the new capabilities that have been created within the national innovation system (NIS). We explain how the role and the capabilities of the French Government Agency for Defence (Direction Generale de l'Armement—DGA) have developed from “project architect” to “project manager”. These new capabilities create new interactions in the French defence innovation system and new roles for the DGA.Technological systems, capabilities, knowledge, government agency, co-evolution, national innovation system, defence, institutional change,

Does the Program Manager Matter? New Public Management and Defense Acquisition

The article of record as published may be found at https://doi.org/10.1177/0275074015596376Past efforts to reform defense acquisition have been based in New Public Management assumptions that certain attributes of program managers (PMs), such as their training and experience levels, are important for improving outcomes. This article documents an effort to examine the relationship between such PM attributes and program outcomes using data drawn from annual Department of Defense Selected Acquisition Reports for major defense acquisition programs between 1997 and 2010. The findings provide little support for these assumptions. They point instead to the potential for institutionalist theories to explain acquisition outcomes, which can enable more nuanced reform policies in the future