Volume Modeling for Rapid Prototyping

The expanding workspace of Rapid Prototyping will draw on the new developments in geometric modeling. Volume modeling has substantial advantages over other modeling schemes to meet the emerging requirements of Rapid Prototyping technology. It provides us with a new approach to design complex geometry and topology. The integration of the volume modeling and Rapid Prototyping technology will help us to fully exploit RP's ability to fabricate objects with complex structures. This paper addresses our research and practice in a volume modeling system toward Rapid Prototyping. Novel techniques in volumetric data manipulation, NURBS volume models and triangular facet generation over solid models are presented. Computer models designed by this system and their corresponding DTM products are also shown atthe end of this paper.Mechanical Engineerin

PVC-LOT-008-J-038

Laser-based powder-bed fusion additive manufacturing or three-dimensional printing technology has gained tremendous attention due to its controllable, digital, and automated manufacturing process, which can afford a refined microstructure and superior strength. However, it is a major challenge to additively manufacture metal parts with satisfactory ductility and toughness. Here we report a novel selective laser melting process to simultaneously enhance the strength and ductility of stainless steel 316L by in-process engineering its microstructure into a crystallographic texture. We find that the tensile strength and ductility of SLM-built stainless steel 316L samples could be enhanced by ~16% and ~40% respectively, with the engineered textured microstructure compared to the common textured microstructure. This is because the favorable nano-twinning mechanism was significantly more activated in the textured stainless steel 316L samples during plastic deformation. In addition, kinetic simulations were performed to unveil the relationship between the melt pool geometry and crystallographic texture. The new additive manufacturing strategy of engineering the crystallographic texture can be applied to other metals and alloys with twinning-induced plasticity. This work paves the way to additively manufacture metal parts with high strength and high ductility.NRF (Natl Research Foundation, S’pore)Published versio

Advanced Sheet Metal Manufacturing using Rapid Tooling 522

A closed loop process is proposed for making sheet metal prototyping parts by using advanced computer aided techniques and computer controlled machines. The key aspect of this process is the method used to fabricate and modify the sheet metal forming tools, which are not necessarily for mass production but should be suitable for short run production or design evaluation of sheet metal products where the prototyping cost and lead-time are greatly reduced. Various approaches are investigated in the preparation of the tooling for onward embossing on a sheet metal. The three indirect approaches use Selective Laser Sintering (SLS), Stereolithography(SLA), and high speed Computer Numerical Controlled (CNC) milling to build the masters from computer data models. And the masters are then served in the vacuum casting process to generate the non-ferrous tooling. The direct approach uses DTM’s RapidSteel to produce the metal tooling without going through any secondary process. Comparisons on quality, leading time and cost are presented.Mechanical Engineerin

The Scalable Modeling of Multi-layer Embedded Capacitor based on LTCC Substrate

Abstract Low temperature co-fired ceramic (LTCC) technology is the preferred platform for integrating multi-layer capacitors due to excellent high frequency performance and low-loss dielectric properties. This letter describes a novel approach to perform modeling of multi-layer capacitors in LTCC technology. This hybrid approach combines both analytical modeling and numerical modeling to provide a scalable circuit model predicting the self-resonance frequency of the multiple dielectric and electrode layers. Good correlation between the simulation results and network analyzer measurements has been also achieved. Introduction Recently, as an alternative solution for the low cost and highly integrated system with multiple functionalities, System-on-Package (SoP) technology has emerged [1] [2]. The SoP brings multiple semiconductor dies of various semiconductor processes and materials, and passive devices such as termination resistors, decoupling capacitors, inductors, waveguide, filters, and antennas into a threedimensional package, to create highly integrated products with optimized cost, size and performance. Markets for the SoP solution include wireless communication, networking, computing, and sensor and storage system applications. To integrate these multiple dies and passive devices into a tiny 3-D SoP, adoption of high-density multilayer substrate design is a common approach to mount the multiple dies on a substrate with the embedded passives, which are laterally or vertically integrated onto the package substrate. Low temperature cofired ceramic (LTCC) technology is the preferred platform for integrating multi-layer passives due to excellent high frequency performance and low-loss dielectric properties In this paper, we propose a scalable modeling method for multi-layer embedded capacitor. Even if many papers have published to accurately model capacitors and their model are quite accurate, none of them has considered the scalability of the model for the multi-layer capacito

Rapamycin synergizes cisplatin sensitivity in basal-like breast cancer cells through up-regulation of p73.

Recent gene expression profiling studies have identified five breast cancer subtypes, of which the basal-like subtype is the most aggressive. Basal-like breast cancer poses serious clinical challenges as there are currently no targeted therapies available to treat it. Although there is increasing evidence that these tumors possess specific sensitivity to cisplatin, its success is often compromised due to its dose-limiting nephrotoxicity and the development of drug resistance. To overcome this limitation, our goal was to maximize the benefits associated with cisplatin therapy through drug combination strategies. Using a validated kinase inhibitor library, we showed that inhibition of the mTOR, TGFβRI, NFκB, PI3K/AKT, and MAPK pathways sensitized basal-like MDA-MB-468 cells to cisplatin treatment. Further analysis demonstrated that the combination of the mTOR inhibitor rapamycin and cisplatin generated significant drug synergism in basal-like MDA-MB-468, MDA-MB-231, and HCC1937 cells but not in luminal-like T47D or MCF-7 cells. We further showed that the synergistic effect of rapamycin plus cisplatin on basal-like breast cancer cells was mediated through the induction of p73. Depletion of endogenous p73 in basal-like cells abolished these synergistic effects. In conclusion, combination therapy with mTOR inhibitors and cisplatin may be a useful therapeutic strategy in the treatment of basal-like breast cancers

Computer aided decoration of ceramic tableware

The objective of this research is to computerise, automate and integrate the processes involved in the decoration of ceramic tableware. Computer usage in the ceramic tableware industry has largely been confined to word processing, spreadsheets, database, payroll, inventory and statistical process control. CAD/CAM or Computer Aided Design and Computer Aided Manufacturing is slowly gaining ground in this industry. The relatively high speed of generating physical designs from conceptuaüsation using CAD/CAM and Rapid Prototyping have suggested their use for the decoration of ceramic tableware.Doctor of Philosophy (GINTIC

Special Issue: NextGen Materials for 3D Printing

Only a handful of materials are well-established in three-dimensional (3D) printing and well-accepted in industrial manufacturing applications. However, recent advances in 3D printable materials have shown potential for enabling numerous novel applications in the future. This special issue, consisting of 2 reviews and 10 research articles, intends to explore the possible materials that could define next-generation 3D printing

Chua, Chee Kai

Prof Chua is the Head of Pillar for Engineering Product Development (EPD) and Cheng Tsang Man Chair Professor at SUTD. His research area is in 3D Printing & Rapid Prototyping or Additive Manufacturing. He is the foremost expert in Singapore in this area and was awarded the prestigious International Freeform and Additive Manufacturing Excellence (FAME) Award in 2018. Prof Chua is also the most published and most cited scientist in “Rapid Prototyping / Additive Manufacturing” (3D Printing) according to the Web of Science. He has published in more than 500 international journals, conference papers, books, book chapters and patents.https://commons.erau.edu/aviasian-bios-2021/1013/thumbnail.jp