Engineering Science and Materials Commons^™

Gas Pressure And Coating Distance For Nanohydroxyapatite Deposition On Stainless Steel 316l Using Flame Spray Technique, Angga Saputra, Utami Dyah Syafitri, Toto Sudiro, Gerald Ensang Timuda, Yessie Widya Sari

Journal of Metals, Materials and Minerals

 Metal implant coating engineering is needed to improve the surface biocompatibility properties of metals.  For this, coating metal surfaces with bioactive and biocompatible biomaterials will be an option. Having high biocompatibility as well as similarity in chemical properties, nanohydroxyapatite may be a candidate as biomaterials for coating the metal implant. The key to the success of metal implant plating is the formation of pores which increase the bioactivity and biocompatibility properties of the implant. In this study, nanohydroxyapatite was used to be coated on stainless steel type 316L (SS316L). To ensure that the coating works properly on the surface, an …

Analysis Of The Impact Factors From The Friction Stir Welding Process For Dissimilar Butt Joints Between Semi-Solid Cast Aluminum 356 And Aisi 1018 Carbon Steel, Worapong Boonchouytan, Jaknarin Chatthong, Rommador Burapa

Journal of Metals, Materials and Minerals

This research aimed to study the impacts of three different rotation speeds of 710, 1000, and 1400 rpm and three welding speeds of 40, 56, and 80 mm·min-1, on dissimilar butt joints between semi-solid aluminum 356 and AISI 1018 carbon steel. Welding tools were made from tungsten carbide material, and the offset was 0 mm. It was found that an increase in the rotation speed and welding speed caused accumulated heat, which led to the appropriate changes in the metallurgical structure. The rotation speed and welding speed factors had the impact on the greater blending of the two metals at …

Laser Powder Bed Fusion Of Ti6al4v-Xcu: Process Parameters, Thywill Ccphas Dzogbewu

Journal of Metals, Materials and Minerals

The original intent of coating biomedical and surgical devices surface with antibacterial agents is to prevent infections. However, the difference in the material properties between the biomedical devices and the coating materials causes the coating material to spall from the biomedical devices. To address the situation, the current research focused on investigating the possibility of using laser powder bed fusion process a subset of additive manufacturing technology to in situ alloy 1 at% Cu with Ti6Al4V. In situ alloying 1 at% Cu with Ti6Al4V would lead to the production of medical and surgical devices with inbuilt antibacterial property. To determine …

Development Of Chemically Grafted Multiwall Carbon Nanotube Onto Cellulose Fiber Sheet And Polyurethane Based Resin Composite For An Active Paper, Siripassorn Sukhkhawuttigit, Sarute Ummartyotin, Yingyot Infahsaeng

Journal of Metals, Materials and Minerals

Cellulose fibers (CFs) and carbon nanotubes (CNTs) were successfully developed on polyurethane substrate as a flexible composite paper. With small amount of CNTs, the composite was prepared by a suction filtration method. The existence of CNT additive in cellulose matrix was investigated based on the correlation of mechanical properties, thermal stability, and electrical properties. Although the highly transparent cellulose sheets impregnated with polyurethane were successfully fabricated, the low transmittance was obtained as the increasing of CNT additive. However, the dielectric properties of composite were enhanced with an addition of CNTs in the composite paper. The electrical conductivity was increased from …

Influence Of Cooling Conditions On Microstructure And Mechanical Property Of Sn-0.3ag-0.7cu Lead-Free Solder, Prajak Jattakul, Tavee Madsa, Piyawan Sunasuan, Niwat Mookam

Journal of Metals, Materials and Minerals

This research has investigated the influence of cooling conditions on the microstructure and mechanical properties i.e., tensile strength and microhardness of Sn-0.3Ag-0.7Cu lead-free solder. In the experiments, casting was performed at 300℃ with comparison between copper and stainless steel molds under slow and fast cooled conditions. X-ray diffractometer confirmed the presence of Cu6Sn5 and Ag3Sn phases in the solder matrix. Lead-free solder solidified under slow cooled conditions exhibited -Sn matrix with larger grain growth as compared to the fast cooled solder. The eutectic area of intermetallic compound (IMC) was found to increase with cooling rate. The tensile strength of slow …

Ab Initio Methylammonium Orientation And Monolayer Effects In Hybrid Perovskite Solar Cells, Jacob M. Artz

Browse all Theses and Dissertations

Methylammonium lead triiodide (MAPbI3) has garnered attention due to their high solar cell efficiencies and low cost to manufacture, but commercialization is not yet possible owing to poor environmental stability. Thus, researchers seek ways which optimize the performance of the MAPbI3 solar cell by modifying the architecture and through interfacial engineering of the charge transport layers. Difficulties in understanding these devices arise from ion migration, charge separation and recombination, and metastable, thermally active precessions of the methylammonium (MA) moiety in the lead iodide framework. In this work, focus is given to the perovskite and an adsorbed monolayer, 2,3,4,5,6-pentafluorothiophenol (C6F5SH), which …

Perceived Importance Of Aac Messages To Support Communication In Rehabilitation Settings, Susan Koch Fager, Judith M. Burnfield, Chase M Pfeifer, Tabatha Sorenson

Department of Mechanical and Materials Engineering: Faculty Publications

Purpose: Permanent or temporary speech loss can occur due to a variety of medical conditions and often requires individuals to use augmentative and alternative communication (AAC) strategies and technologies to support communication. The use of AAC in medical and rehabilitation settings is critical to ensure the health, safety and psychological well-being of communicatively vulnerable individuals.

Method: This study surveyed the perceived importance of communication messages within five categories (Basic Needs, Patient-Provider Specific Communication, Social, Feelings, and Messages for Young Children) by individuals with disability who have undergone recent medical care as well as by rehabilitation care providers.

Results: Results indicated …

Feasibility Of Motor-Assisted Elliptical To Improve Walking, Fitness And Balance Following Pediatric Acquired Brain Injury: A Case Series, Judith M. Burnfield, Guilherme Manna Cesar, Thad W. Buster

Department of Mechanical and Materials Engineering: Faculty Publications

Purpose: Walking, fitness, and balance deficits are common following acquired brain injury (ABI). This study assessed feasibility, acceptability, and usefulness of a modified motor-assisted elliptical (ICARE) in addressing walking, fitness, and balance deficits in children with chronic ABIs.

Methods: Three children (> 5 years post-ABI) completed 24 ICARE exercise sessions (exercise time, speed, and time overriding motor-assistance gradually increased) to promote mass repetition of gait-like movements and challenge cardiorespiratory fitness. Parents’ and children’s perceptions of ICARE’s safety, comfort, workout, and usability were assessed. Cardiovascular response, gait and balance outcomes were assessed.

Results: No adverse events occurred. Parent’s …

Ultrasound-Activated Ciliary Bands For Microrobotic Systems Inspired By Starfish, Cornel Dillinger, Nitesh Nama, Daniel Ahmed

Department of Mechanical and Materials Engineering: Faculty Publications

Cilia are short, hair-like appendages ubiquitous in various biological systems, which have evolved to manipulate and gather food in liquids at regimes where viscosity dominates inertia. Inspired by these natural systems, synthetic cilia have been developed and utilized in microfluidics and microrobotics to achieve functionalities such as propulsion, liquid pumping and mixing, and particle manipulation. Here, we demonstrate ultrasound-activated synthetic ciliary bands that mimic the natural arrangements of ciliary bands on the surface of starfish larva. Our system leverages nonlinear acoustics at microscales to drive bulk fluid motion via acoustically actuated small-amplitude oscillations of synthetic cilia. By arranging the planar …

Artificial Reefs: A History, A Science, A Technology, Mairead D. Farrell

Honors Theses

Over the past 60 years, artificial reefs have expanded beyond the definition of a technology, and in turn have developed into a unique branch of marine science. To better emphasize this growth and separation, a brief history of artificial reef development and usage in chapter two shows some of the key shifts over time in this technology’s purpose and the materials used to achieve that goal. Likewise, to indicate the scientific development of artificial reefs as a branch of marine science, their usage for discovery and research is recorded in chapter three, along with the exponential increase in published scientific …

Topological Design Of Pentamode Lattice Metamaterials Using A Ground Structure Method, Zuyu Li, Zhen Luo, Lai-Chang Zhang, Chun-Hui Wang

Research outputs 2014 to 2021

Pentamode metamaterials are a new class of artificially engineering three-dimensional lattice composites. There exist a few types of pentamode metamaterials that are dominated by ad hoc design motifs, while a systematic design approach is still missing. This paper will present an efficient topological optimization methodology to discover a series of novel pentamode lattice microarchitectures over a range of effective material properties. Firstly, the necessary and sufficient condition that is required for elasticity constants of pentamode micro lattices with at least elastically orthotropic symmetry is derived. Secondly, a general mathematical formulation for design optimization of such pentamode micro lattices is developed. …

การประยุกต์ใช้แผ่นที่ปรับค่าความแข็งด้วยลมเข้ากับมือจับแบบง่าย, เจตนิพิฐ อรุณรัตน์

Chulalongkorn University Theses and Dissertations (Chula ETD)

จากแนวคิดการใช้งานผิวหนังเทียมหรืออุปกรณ์ห่อหุ้มเพื่อเพิ่มความปลอดภัยและประสิทธิภาพในการทำงานของหุ่นยนต์ นำมาสู่การพัฒนาผิวหนังเทียมที่ติดตั้งบริเวณมือจับของหุ่นยนต์ โดยผิวหนังเทียมเหล่านี้จะมีค่าความแข็งที่แตกต่างกันตามการใช้งาน วิทยานิพนธ์เล่มนี้นำเสนอการออกแบบและขึ้นรูปแผ่นที่ปรับค่าความแข็งได้ (VSPs) ด้วยความดันลม ซึ่งทำหน้าที่เสมือนเป็นผิวหนังเทียมของมือจับ จากนั้นนำแผ่นดังกล่าวไปทดลองใช้กับมือจับแข็งเกร็งอย่างง่าย เพื่อหยิบจับวัตถุซึ่งไม่ทราบตำแหน่ง รูปทรงและความแข็งที่แน่ชัดด้วยวิธีการควบคุมอิมพีแดนซ์ VSPs สร้างขึ้นจากวัสดุอ่อนนุ่มประเภทซิลิโคน ซึ่งขึ้นรูปโดยใช้การหล่อและเสริมความแข็งแรงด้วยเส้นใยไฟเบอร์ มีโครงสร้างภายในเป็นทรงกระบอกเรียงตัวขนานกัน สามารถควบคุมค่าความแข็งผ่านการควบคุมค่าความดันโดยใช้ปั๊มเข็มฉีดยาร่วมกับตัวควบคุมแผนเลื่อน จากการทดลองประยุกต์ใช้ VSPs ร่วมกับมือจับแข็งเกร็งพบว่า VSPs ช่วยเพิ่มความปลอดภัยและความยืดหยุ่นในการทำงาน เนื่องจากสามารถปรับค่าความแข็งให้เหมาะสมกับการทำงานนั้น ๆ ได้ โดยการปรับค่าความแข็งเพิ่มจะช่วยลดระยะเวลาในการทำงาน หากลดค่าความแข็งจะช่วยเพิ่มความปลอดภัยและความเสถียรในการทำงานแทน

การระบายความร้อนของเเผ่นเรียบด้วยโครงสร้างเชือกดูดซับน้ำ, ชลธิชา แกล้วทนงค์

Chulalongkorn University Theses and Dissertations (Chula ETD)

การศึกษาครั้งนี้มีวัตถุประสงค์เพื่อศึกษาการประยุกต์อุปกรณ์ระบายความร้อนระเหยน้ำจากผ้ากับเซลล์แสงอาทิตย์ งานวิจัยนี้ได้แบ่งการศึกษาออกเป็น 2 ส่วนด้วยกันคือ การศึกษาส่วนแรกเป็นการทดสอบผลของอุปกรณ์ระบายความร้อนระเหยน้ำจากผ้ากับเซลล์แสงอาทิตย์จำลอง และการศึกษาในส่วนที่ 2 เป็นการเสนอการประยุกต์อุปกรณ์ระบายความร้อนระเหยน้ำจากผ้ากับเซลล์แสงอาทิตย์ ซึ่งได้นำเสนอต้นแบบการประยุกต์อุปกรณ์ระบายความร้อนระเหยน้ำจากผ้ากับเซลล์แสงอาทิตย์โดยมี 3 รูปแบบ รูปแบบที่ 1 คือกรณีติดตั้งบนดาดฟ้าอาคารเรียบโดยใช้ระบบน้ำร่วมกับอาคาร รูปแบบที่ 2 คือกรณีติดตั้งบนดาดฟ้าอาคารเรียบโดยแยกระบบน้ำกับอาคาร และรูปแบบที่ 3 คือกรณีติดตั้งบนหลังคาที่มีความลาดเอียงโดยแยกระบบน้ำกับอาคาร และวิเคราะห์ความคุ้มค่าทางเศรษฐศาสตร์ โดยวิเคราะห์มูลค่าปัจจุบันสุทธิ (NPV) อัตราผลตอบแทนภายใน (IRR) วิเคราะห์ระยะเวลาคืนทุน (Payback Period) และวิเคราะห์ความอ่อนไหวของโครงการ การทดสอบอุปกรณ์ระบายความร้อนระเหยน้ำจากผ้ากับเซลล์แสงอาทิตย์จำลองแสดงให้เห็นว่าสำหรับกรณีฟลักซ์ความร้อน 205.8, 483.8 และ 661.8 W/m2 สามารถลดอุณหภูมิของแผงได้ถึง 5.9, 8.3 และ 11.3°C ซึ่งประมาณได้เป็นการเพิ่มประสิทธิภาพเซลล์แสงอาทิตย์ 2.95, 4.15 และ 5.65% ตามลำดับ และผลการวิเคราะห์ความคุ้มค่าทางเศรษฐศาสตร์ของประยุกต์อุปกรณ์ระบายความร้อนระเหยน้ำจากผ้ากับเซลล์แสงอาทิตย์ตัวอย่างที่ขนาดการติดตั้ง 6.6 kW ตลอดอายุโครงการ 25 ปี แสดงให้เห็นว่าการติดตั้งในรูปแบบที่ 1 คือกรณีติดตั้งบนดาดฟ้าอาคารเรียบโดยใช้ระบบน้ำร่วมกับอาคาร มีค่า NPV สูงสุด IRR มากสุด และระยะเวลาคืนทุนน้อยสุด ได้แก่ 109,112.11 บาท, 255.33% และ 0.39 ปี ตามลำดับ ในการวิเคราะห์ความอ่อนไหวโครงการที่พิจารณาผลกระทบจากการเปลี่ยนแปลงค่าไฟฟ้า ค่าน้ำ และค่าผลกระทบของอุณหภูมิต่อประสิทธิภาพเซลล์แสงอาทิตย์ พบว่า ค่าผลกระทบของอุณหภูมิต่อประสิทธิภาพที่เปลี่ยนไปส่งผลต่อ NPV, IRR และระยะเวลาคืนทุนมากที่สุด โดยที่การเปลี่ยนแปลงค่าน้ำมีผลกระทบน้อยที่สุด

A Numerical Study Of Flow Past Arrays Of Cylinders At Low Reynolds Number, Woraphon Wannaviroj

Chulalongkorn University Theses and Dissertations (Chula ETD)

Coastal erosion along shorelines has increasingly been prevalent. A popular method for alleviating this problem is to use breakwaters, made of bamboo, known as “bamboo fencing”. The thesis numerically investigates steady, low-velocity flow past several geometrical configurations of bamboo fencings, modelled as array of cylinders using the ANSYS®-Fluent software. The Reynolds number based on incoming flow velocity (U∞), cylinder diameter (D), and fluid kinematic viscosity is Re = 100. Validation is done for mesh convergence and time-step size for the two-dimensional flow past a circular cylinder. For a pair of side-by-side arranged cylinders, it is found that the effect of …

Using Machine Learning To Interpret Dice Rolls, Hunter Wimsatt, Aarohi Panzade, Kaaustaaub Shankar, Warren Campbell

SEAS Faculty Publications

Gamers use polyhedral dice that come with 4 sides (D4), 6 sides (D6), 8 sides (D8), 10 sides (D10), 12 sides (D12) and 20 sides (D20). All dice are unfair, some more than others. The goal of this project was to develop a machine learning and computer vision solution for the interpretation of dice rolls. When combined with an automated dice roller it would facilitate the study of dice unfairness. In the machine learning literature, Convolutional Neural Networks (CNNs) are the preferred method of computer classification of images. The CNN convolves images with different weights and biases through multiple layers …

Preperitoneal Insufflation Pressure Of The Abdominal Wall In A Porcine Model, Riley E. Reynolds, Benjamin Wankum, Sean J. Crimmins, Mark A. Carlson, Benjamin S. Terry

Department of Mechanical and Materials Engineering: Faculty Publications

Background Most complications and adverse events during laparoscopic surgery occur during initial entry into the peritoneal cavity. Among them, preperitoneal insufflation occurs when the insufflation needle is incorrectly placed, and the abdominal wall is insufflated. The objective of this study was to find a range for static pressure which is low enough to allow placement of a Veress needle into the peritoneal space without causing preperitoneal insufflation, yet high enough to separate abdominal viscera from the parietal peritoneum.

Methods A pressure test was performed on twelve fresh porcine carcasses to determine the minimum preperitoneal insufflation pressure and the minimum initial …

Lightning Strike Response Of Composite Structures: A Review, Akhileshwar Pandey, Ashutosh Kumar Upadhyay, Karunesh Kumar Shukla

Journal of Metals, Materials and Minerals

Wind turbines and aircraft are generally made of less conductive carbon/glass composites. Significant damages may occur to these materials if they are struck by high energy lightning strikes. Damage and structural response of composites is essentially a multiphysics domain, involving thermal, electrical, magnetic and structural analysis. In this article, the fundamental physics of lightning, multiphysics analysis, numerical implementation and experimental studies about composite materials are reviewed. The relevant international standards and possible characterization methods of lightning strike damage are also reproduced in this article. In addition to this, the current and prospective technologies, to protect composite from lightning strikes are …

Wear Behavior Of Aluminium 6061 Alloy Reinforced With Coated/Uncoated Multiwalled Carbon Nanotube And Graphene, Vijee Kumar, Kempaiah Ujjaini Nagegowda, Satish Babu Boppana, Ramesh Sengottuvelu, Palanikumar Kayaroganam

Journal of Metals, Materials and Minerals

The current study deals with the fabrication and investigation of wear characteristics of Aluminium 6061(Al6061) hybrid metal matrix composites (MMCs) processed through powder metallurgy technique. Al6061 hybrid MMCs involving fixed 2 wt% of coated/uncoated multiwalled carbon nanotubes (MWCNTs) and varying weight percentages of graphene were fabricated through ball milling procedure. To enhance the scattering of MWCNTs in the matrix, MWCNTs were coated by means of copper through electroless deposition method. Dry sliding wear conduct of Al6061 MMCs was investigated using a pin-on-disc wear testing machine. It was found that at lower load, composites exhibited lower wear resistance than base alloy …

Improvement On Cost-Performance Ratio Of Fiberglass/Carbon Fiber Hybrid Composite, Nathawat Poopakdee, Warut Thammawichai

Journal of Metals, Materials and Minerals

Fiberglass composite (FG) is widely used as a metal substitute in general applications due to its corrosion and chemical resistance, relatively high strength, and low cost. Still, the FG is deficient in performance and relatively heavy for airframes. Carbon fiber composite (CF) is utilized instead as it has greater performance and lower weight. However, the CF is brittle and expensive. Thus, in this work, we combine FG and CF into two types of hybrid composites to achieve a cost-effective solution with greater or comparable mechanical properties to those of CF. The first one uses FG as core and CF as …

Efficiency Of Tri-N-Octylamine For The Liquid-Liquid Extraction Of Co (Ii) From Acidic Chloride Medium, Aishwarya Mishra, Nilam Swain, Sanghamitra Pradhan, Sujata Mishra

Journal of Metals, Materials and Minerals

Cobalt criticality is increasing as a function of time and this concern has impelled researchers to ascertain efficient recovery schemes of cobalt. In this paper, an extraction strategy for cobalt utilizing tri-n-octyl amine (TOA) in kerosene from acidic chloride media has been developed. The extraction percentage was found to be 76.7 using 1.5M TOA. The extracted species has been formulated as (R3NH) CoCl3 based on the findings of slope analysis. Influence of various salting out agents like NH4Cl, KCl, and NaCl on the percentage extraction has been analysed and KCl emerged as beneficial for extraction. The estimated values of enthalpy …