As 3-D printed materials are being embraced by the manufacturing industries, understanding the response mechanism to high strain rate events becomes a concern to meet requirements for a specific application. In order to improve the mechanical performance of a 3-D printed part, it is necessary to quantify the impact of various printing parameters on the mechanical properties. Initial studies have shown that a difference in 3-D printed material is expected due to the effect of manufacturing parameters such as anisotropy relating to printing direction, infill pattern, infill percentage, layer height and orientation of the part being printed. The main focus of the study is to characterize the effect of the previously mentioned printing parameters under quasi-static and high strain rate (100–1000 /s). In this strain rate regime, the most common apparatus used is the Split Hopkinson pressure bar (also known as Kolsky bar). It consists of a cylindrical metallic bar that has a striker, input and output bar. While the specimen is fixated between the input and output bar, the striker bar is accelerated and triggers the incident bar. As a result, an elastic wave is generated which travels towards the specimen/input bar interface, where some part of it is reflected and the rest is transmitted. The Kolsky bar is adjusted by using a hollow transmitter tube and pulse shaper. Due to an impedance mismatch between the samples and bar material, the amplitude of the transmitted pulse is low. Using a hollow transmitter bar increases this amplitude due to area mismatch between the specimen and tube. Using a pulse shaper between the striker and input bar, the rise time of the elastic compressive wave increases and assists in achieving a constant rate of loading. The compressive stress strain curves were obtained under high strain rates to determine the strain rate effect. To measure the response under static testing conditions, a commercial load frame was used. A comprehensive comparison of dynamic compressive response of samples was performed to characterize the effect of printing parameters.
Engineering practice and design in particular have gone through several changes during the last two decades whether due to scientific achievements including the evolution in novel engineering materials, computational advancements, globalization and economic constraints as well as the strategic needs which are the drive for innovative engineering. All these factors have impacted and shaped to certain extent the educational system in North America and Canada in particular. Currently, high percentage of the engineering graduates would require extensive training in industry to be able to conduct reliable complex engineering designs supported by scientific verification and validation, understand the complete design stages and phases, and identify the economic and cultural impact on such designs. This task, however, faces great challenges without educational support in such vastly changing economy.Lots of attention has been devoted to engineering design education in the recent years to incorporate engineering design courses supported by team design projects and capstone projects. Nevertheless, the lack of integrated education system towards engineering design programs can undermine the benefits of such efforts. In this paper, observations and analysis of the challenges in engineering design are presented from both academic and industrial points of view. Furthermore, a proposed vertical and lateral engineering education program is discussed. This program is structured to cover every year of the engineering education curricula, which emphasizes on innovative thinking, design strategies, support from and integration with other technical engineering courses, the use of advanced analysis tools, team collaboration, management and leadership, multidisciplinary education and industrial involvement. Its courses have just commenced for freshmen engineering students at the newly launched Mechanical Engineering Department at the Lassonde School of Engineering, York University.
The refractory system in blast furnace hearth is subject to harsh conditions including chemical attack and thermal / mechanical loads. The longevity of hearth is vitally important in achieving the target furnace campaign life and avoiding premature and costly repairs. Consequently, it is important to monitor the hearth refractory wear including the temperature distribution andprotective skull formation. This paper presents a novel approachto simultaneously utilizeAcousto-Ultrasonic Echo (AU-E) non-destructive examination and thermocouple / cooling system data to improve accuracy of hearth refractory wear predictions in operating blast furnaces. Example applications of this assessment methodology on blast furnaces are discussed. This assessment methodology is widely used to help prolong the blast furnace campaign life.
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