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The purpose of this paper is to introduce the multi-solution nature of topology optimization (TO) as a design tool for additive manufacturing (AM). The sensitivity of…
The purpose of this paper is to introduce the multi-solution nature of topology optimization (TO) as a design tool for additive manufacturing (AM). The sensitivity of topologically optimized parts and manufacturing constraints to the initial starting point of the optimization process leading to structures with equivalent performance is explored.
A modified bi-directional evolutionary structural optimization (BESO) code was used as the numerical approach to optimize a cantilever beam problem and reduce the mass by 50 per cent. Several optimized structures with relatively equivalent mechanical performance were generated by changing the initial starting point of the TO algorithm. These optimized structures were manufactured using fused deposition modeling (FDM). The equivalence of strain distribution in FDM parts was tested with the digital image correlation (DIC) technique and compared with that from the modified BESO code.
The results confirm that TO could lead to a wide variety of non-unique solutions based on loading and manufacturability constraints. The modified BESO code was able to reduce the support structure needed to build the simple two-dimensional cantilever beam by 15 per cent while keeping the mechanical performance at the same level.
The originality of this paper lies in introduction and application of the multi-solution nature of TO for AM as a design tool for optimizing structures with minimized features in the overhang condition and the need for support structures.
The purpose of this paper is to explore the possibility of integrating inkjet printed circuitry with fused deposition modeling (FDM) structures to produce embedded…
The purpose of this paper is to explore the possibility of integrating inkjet printed circuitry with fused deposition modeling (FDM) structures to produce embedded electronics and smart structures. Several of the challenges of combining these technologies are identified, and potential solutions are developed.
An experimental approach is taken to investigate some of the relevant physical processes for integrating FDM and inkjet deposition, including the printing, drying and sintering processes. Experimental data are collected to assist understanding of the problems, and engineering solutions are proposed and implemented based on the gained understanding of the problems.
Three challenges have been identified, including the discontinuity of the printed lines resulting from the irregular surface of the FDM substrate, the non-conductivity of the printed lines due to the particle segregation during the droplet drying process and the slow drying process caused by the “skinning effect”. Two engineering solutions are developed for the discontinuity problem. The non-conductivity issue and the slow drying process are attributed to the motion of the nanoparticles caused by the evaporation flow. The thermally activated drying process for the Cabot ink suggests that the proposed solution is effective. Timescale analysis and experimental data show that the printing conditions do not have a clear influence on the conductivity of the printed lines, and drying and sintering processes are more important.
No quantitative model has yet been developed for simulating the printing, drying and sintering processes associated with inkjet printing on FDM substrates. Quantitative models can be extremely valuable for improvement in understanding the problems, optimizing the proposed solutions and coming up with better solutions.
The research findings in this work have great implications in implementing a hybrid FDM-inkjet deposition machine for fabricating embedded electronics and smart structures. All the proposed engineering solutions for the identified problems can be potentially integrated into one machine.
The success of the integration of the FDM and inkjet deposition process will enable the design of compact electro-mechanical structures to replace the large heavy electro-mechanical systems.
This work represents one of the first attempts for integrating inkjet deposition of silver nanoparticle inks with the FDM process for making compact electro-mechanical structures. Three critical challenges are identified, and corresponding engineering solutions are proposed and implemented based on analysis of the relevant physical processes, including the printing, drying and sintering processes, which has laid the foundation for integrating the FDM and inkjet deposition processes.
Ultrasonic additive manufacturing (UAM) is a rapid prototyping process through which multiple thin layers of material are sequentially ultrasonically welded together to…
Ultrasonic additive manufacturing (UAM) is a rapid prototyping process through which multiple thin layers of material are sequentially ultrasonically welded together to form a finished part. While previous research into the peak temperatures experienced during UAM have been documented, a thorough examination of the heating and cooling curves has not been conducted to date.
For this study, UAM weldments made from aluminum 3003‐H18 tapes with embedded Type‐K thermocouples were examined. Finite element modeling was used to compare the theoretical thermal diffusion rates during heating to the observed heating patterns. A model was used to calculate the effective thermal diffusivity of the UAM build on cooling based on the observed cooling curves and curve fitting analysis.
Embedded thermocouple data revealed simultaneous temperature increases throughout all interfaces of the UAM build directly beneath the sonotrode. Modeling of the heating curves revealed a delay of at least 0.5 seconds should have existed if heating of lower interfaces was a result of thermal diffusion alone. As this is not the case, it was concluded that ultrasonic energy is absorbed and converted to heat at every interface beneath the sonotrode. The calculated thermal diffusivity of the build on cooling was less than 1 percent of the reported values of bulk aluminum, suggesting that voids and oxides along interfaces throughout the build may be inhibiting thermal diffusion through thermal contact resistance across the interface.
This work systematically analyzed the thermal profiles that develop during the UAM process. The simultaneous heating phenomenon presented here has not been documented by other research programs. The findings presented here will enable future researchers to develop more accurate models of the UAM process, potentially leading to improved UAM bond quality.
The case explores information technology (IT) company Mindtree’s journey of 20 years from the time it was founded in 1999 to be different from others, and how it became a…
The case explores information technology (IT) company Mindtree’s journey of 20 years from the time it was founded in 1999 to be different from others, and how it became a target for acquisition by an Indian diversified conglomerate in 2019. It offers insights into developing organizational culture and values in an organization, threats faced by a company when promoters dilute their shareholding, and the strategies followed by the acquirer and the target firm. It also deals with the challenges in the acquisition of a knowledge service digital firm. After working through the case and assignment questions, students will be able to: identify the circumstances under which a company can become a target for hostile takeover; describe motivations of the acquirer firm in an acquisition; distinguish between acquisition and hostile takeover, and discuss salient features of Securities and Exchange Board of India (substantial acquisition of shares and takeover) regulations, 2011; list the defenses a target firm can adopt to ward off hostile acquirer; explore strategies followed by acquirer and target firms; analyze important ingredients of organization culture, and importance of cultural congruence in an acquisition; and discuss challenges faced by an acquirer in India, namely, legal, retention of clients and key people in the target firm particularly in hostile environment.
The case explores how ten IT professionals founded mid-tier IT services company Mindtree in 1999 in Bengaluru, India (home to Infosys and Wipro) to be different from others – by inserting themselves at a higher level in the value chain, being philanthropic as a part of broader business strategy to attract a certain kind of employee and customer. It developed a culture of equality, consideration and respect. Its attrition rate of 12 to 13 per cent was significantly lower than the Industries. Mindtree crossed annual revenue of US$1bn for FY 2019 and was growing at twice the industry’s growth rate. The most attractive part was that its proportion of revenue from digital services was about 50 per cent as compared to 25-35 per cent of other services vendors. With time, the share of promoters/founders declined and increased one investor’s shareholding of V. G. Siddhartha and his related entities. In early March 2019, the promoters’ stake was 13.32 per cent while Siddhartha had 20.32 per cent. Larsen and Toubro (L&T) one of India’s conglomerate entered into a share purchase agreement on March 18, 2019 with Siddhartha to acquire his 20.32 per cent stake. Immediately, L&T asked its broker to purchase up to 15 per cent of share capital of Mindtree at a price not exceeding INR 980 per share (each share of face value INR 10). This would trigger an open offer by L&T to purchase additional 31 per cent shares of Mindtree. The action of hostile takeover bid by L&T evoked emotional criticism from Mindtree founders. Mindtree efforts to defend itself could not materialize. L&T’s stake crossed 26 per cent on May 16, 2019. After Indian regulator SEBI’s approval, L&T’s open offer to buy shares from Mindtree shareholders commenced on June 17, 2019. The case examines motivation of the acquirer firm particularly when it is a conglomerate, and how a well-performing company became a target for hostile takeover. It looks at vulnerabilities of a target firm, and defensive steps a firm can take to fence itself against such takeover. The case also explores how organizational culture is built in a people-oriented business, namely, digital services, and what role it plays in a merger of two firms.
Complexity academic level
The case is suited for postgraduate students of management, as well as those undergoing executive courses in management.
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CSS 11: Strategy.