Prof. Takahiro Ohashi
Head of Mechanical Engineering Department, Kokushikan University, Japan
Biography: Prof. Takahiro Ohashi is Head of Mechanical Engineering Department at Kokushikan University. Prof. Takahiro Ohashi is one of the representative delegate of Japan Society for Technology of Plasticity from April 2016 to now. Also, he is the board of trustees of Aluminum Forging Association in Japan. Prof. Takahiro Ohashi experienced in directing a national research project for a new die structure of Ministry of Economy, Trading and Industry (METI), as well as experienced in directing 3 research teams of National Institute of Advanced Industrial Science and Technology (AIST). Meanwhile, Prof. Takahiro Ohashi gained the Best Paper Award in ICAMEM2016 at April 2016, and won the Second Paper Award in ICMEA2016 at September.
Speech Title: Proposal of "Easily-Decomposable Dissimilar-Materials-Joining" Concept with Friction Stir Forming
Abstract: Recently, joining dissimilar materials, including steel, CFRP, and aluminum alloy, has been successfully studied due to multiple materials used in the structure of automobiles. The material ratio of normal steel in a car exceeds 60% now; however the U.S. government predicts that it will fall into less 20% in next 20 years. However, it is natural to imagine that such multiple-material products will be a problem for recycling in future. Joining the materials more tightly and wholly makes it more difficult to separate them in the recycling procedure. Therefore, it is worthwhile to discuss methods for easily decomposable joined dissimilar materials. This presentation provides a framework of the "easily-decomposable dissimilar-materials-joining" with friction stir forming approaches. Friction-stir forming (FSF) is a friction-stir process invented by Nishihara in 2002. In FSF, a material is put on a die, and friction stirring is then conducted on its back surface. The material deforms and precisely fills the cavity of the die due to high pressure and heat caused by friction stirring. Materials in the process often display outstanding deformability and moldability. In the presentation, the authors will suggest utilizing the process for the fabrication of a hook-like mechanical joint that can be separated simply by sliding the joined materials each other. Additional opposite hooks generated by the above approach or additional location pins prevent joined members from sliding, and the hooks join them tightly. In recycling, the materials can be separated smoothly by sliding materials each other after cutting them between the hooks, or destroying / removing the location pins. The above separating procedure can be made more complicated for safety with adding more opposite hooks in various direction or more location pins. The presentation also provides some examples of "easily-decomposable dissimilar-materials-joint" and evaluations of their strength.
Prof. Hisaki Watari
Tokyo Denki University, Japan
Biography: Hisaki Watari has received his PhD in Mechanical System Engineering, from Gunma University, Japan in 2006. He has been researching into properties of magnesium alloy by rapid cooling by using twin roll casting in these fifteen years in Gunma University and Oyama National Colleague of Technology in Japan, in UMIST in the UK. He is now the chair of the Japan Association of Aluminum Forging Technology. He has published more than 130 papers in journals and conducting works relating metal forming of light metals, such as aluminum and magnesium alloys.
Speech Title: Future possibilities of Magnesium alloys in the transportation industry
Abstract: A total weight reduction approach has been a key issue for car manufacturers to cope with more and more stringent requirements for the protection of the planet. In recent years, production of magnesium alloy sheet still remains at a very low level, although production of magnesium has risen dramatically. The aim of the study is to confirm future possibilities of practical use of magnesium alloys by using hot forging technology to manufacture alloy producs, which will contributes to dramaticlally reduce proidust CO2 emission. Characteristic feature of hot forging of twin roll cast magnesium alloys which have relatively high aluminium content has been investigated. High tensile strength magnesium alloys containing 9 to 12% aluminum, such as AZ91, AZ101, AZ111, and AZ121 have been developed by rapid cooling process using a horizontal twin roll caster. A new experiment was performed for hot forging of high strength magnesium alloys with high aluminum content. From the results, using magnesium alloys with high aluminum content yielded less compressive deformation resistance than conventional magnesium alloys. It was also demonstrated that hot forging of magnesium alloys with high aluminum content produces small magnesium crystals (about six micro meters) and crystallized substances. The mean grain size of the microstructure of AZ121 forged at 623K was less ten micrometers although that of the AZ91 was about thirty micrometers. The small beta phase which precipitates in the twin roll cast AZ121 was distributed uniformly comparing to AZ91. Microscopic observation of the forged products, it has been cralified that the Hall-petch rule between mean grain size of forged materials and Vickers hardness has been proved. The effects of the dynamic recrystallization on the microstructures of the twin roll cast products has been disucussed. It has also been clarified that high aluminium content magnesium alloys could be used for original materials for hot forging. It has been found that the effects of aluminum content affects pricipitaion of beta phase as well as grain size.
Prof. Muhammad Yahaya
Emeritus Professor in School of Applied Physics, UKM Malaysia, Malaysia
Biography: Dr Muhammad Yahaya is an Emeritus Professor of Physics at Universiti Kebangsaan. Dr Muhammad Received his Ph.D at Monash University in 1979 and Drs from ITB, Indonesia in 1973. Dr Muhammad has 35 years of teaching and research experience with Universiti Kebangsaan Malaysia , Brown University, USA, Monash University, Australia. He was appointed Head of Physics Department (74-79), Deputy Dean, Center of Postgraduate studies (1994-1999), Director, Research Management Centre, (1999-02) Director, Centre of Academic Advancement, (02-07). Dr Muhammad maintains a diverse research interest including thin films, electronic property of metals, solar energy and computer in physics communication. Dr Muhammad holds membership to various organizations and institutions. He is actively involved in Physics and Science Terminology, Writing Malay language Text book in Physics. Dr Muhammad is currently a member of editorial board, UKM. He was a former president of Malaysian Solid State Science and Technology (1991-2012), Fellow Malaysian Institute of Physics, member IEEE and member Malaysia Materials Science. Dr. Muhammad has received many awards for his academic and professional excellence. He received commonwealth Scholarship and Fellowship plan to pursue his Ph.D (1975) DAAD -German Fellowship (1984), Fullbright fellowship (1984-1985), JSPS Fellowship and Associate member of ICTP,Italy, Fellow, Academy Science Malaysia (2006-now), KMN (1995) Anugerah KMN (1995),Tokoh Ilmuan MABBIM (1997),Award, Recognition of Service UKM (1999),ANS- Negeri Sembilan (2004), Award 'Prominent Physics Figure-UPM (2005)-100 years world year of physics, DSPN (Dato' Penang (2007).
Prof. Dr. Sinin Hamdan
Universiti Malaysia Sarawak, Malaysia
Biography: Prof. Dr. Sinin Hamdan focus on the field of specialization is Mechanics of Materials based on his PhD in that area from Loughborough University of Technology, Loughborough, England (1994). That educational experience with his MSc in Welding and Adhesive Bonding of Engineering Materials from Brunel University, London (1986) and BSc in Physics (1984) from Universiti Kebangsaan Malaysia allow him to retool himself to fit into Universiti Malaysia Sarawak (UNIMAS) priority area of Materials and Manufacturing when he joined this university in 2001. Prof. Dr. Sinin Hamdan attended a 6 months scientist exchange program (post doc) under Japanese Society for Promotion of Science (JSPS/VCC) in 1999 at Wood Physics Laboratory, Kyoto University and obtained a good experience working with wood physics. From 9-31 March 2003, Prof. Dr. Sinin Hamdan went to Wood Research Institute, Kyoto University, Japan (under Japanese Society for Promotion of Sciences-JSPS) to study The Application of Acoustic Emission Monitoring to Forest Product Research. From 7 May-7 Jun 2007, Prof. Dr. Sinin Hamdan work with Collaboration on Dynamics, Materials and Machining GeM Laboratory, Ecole Central Nantes (ECN), Nantes France. From 1 august-31 october 2012, he worked on gamelan in Physics Laboratory, Loughborough University.
Abstract: Jute cellulose composite (JCC), bamboo cellulose composite (BCC), untreated hybrid jute-bamboo fiber composite (UJBC), and jute-bamboo cellulose hybrid biocomposite (JBCC) were fabricated. All cellulose hybrid composites were fabricated with chemical treated jute-bamboo cellulose fiber at 1:1 weight ratio and low-density polyethylene (LDPE).The effect of chemical treatment and fiber loading on the thermal, mechanical, and morphological properties of composites was investigated. Treated jute and bamboo cellulose were characterized by Fourier transform infrared spectroscopy (FTIR) to confirm the effectiveness of treatment. All composites were characterized by tensile testing, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Additionally, surface morphology and water absorption test was reported. The FTIR results revealed that jute and bamboo cellulose prepared are identical to commercial cellulose. The tensile strength and Young’s modulus of composites are optimum at 10 weight percentage (wt%) fibers loading. All cellulose composites showed high onset decomposition temperature. At 10 wt% fiber loading, JBCC shows highest activation energy followed by BCC and JCC. Significant reduction in crystallinity index was shown by BCC which reduced by 14%. JBCC shows the lowest water absorption up to 43 times lower compared to UJBC. The significant improved mechanical and morphological properties of treated cellulose hybrid composites are further supported by SEM images. Hybrid composites were fabricated by hexamethylene diisocyanate (HDI) treated jute–bamboo fiber, nanoclay, tin(IV) oxide nanopowder, and low-density polyethylene. The composites were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, and differential scanning calorimetry. Surface morphology, tensile testing, and water absorption test were also reported. FTIR results revealed that treated fiber had covalence bonding with polymer matrix which enhanced mechanical properties. All HDI treated hybrid composites showed significant improvement in activation energy, lower crystallinity index, significant high tensile strength, and Young’s modulus compared to untreated hybrid composites. All treated hybrid composites also showed extreme low water absorption. The addition of nanoclay or tin(IV) oxide into treated hybrid composites had a negative impact on thermal-mechanical properties. Surface morphological results revealed the bonding condition among hybrid composites.
Prof. Yong-Shin Lee
Kookmin University, Korea
Biography: Prof. Yong-Shin Lee received his BS from Seoul National University in Korea, MS from Korea Advanced Institute of Science and Engineering (KAIST) in Korea, and Ph. D. from Cornell University in the United States of America. He worked at Samsung Engineering Co., and Korea Institute of Science and Engineering (KIST), before he joined the School of Mechanical Engineering, Kookmin University in 1992. Since then, he served as a Dean in the College of Engineering, as a Dean in the Graduate School of Engineering, Kookmin University. He also served as a President of Korean Society for Technology of Plasticity (KSTP). He has been working on the process design for metal forming such as rolling, extrusion/drawing, forging, and so forth. The specialty in his process model is the incorporation of micro structural developments such as texture development and damage evolution. He also developed a damage evolution model, a new penalty contact model, a new diffusion bonding model in terms of temperature and plastic work dissipation, and a constitutive relation for powder metallurgy.
Abstract: Pearlitic steel wires have been widely used for a main cable of a suspension bridge, a reinforcement wire of concrete or tire, and other structural wires requiring high strength. The mechanical properties, such as strength and ductility, of a pearlitic steel wire depend strongly on its microstructures. The high strength of pearlitic steel wire is obtained by the band-shaped cementite, which exist between the matrix of ferrite just like a laminated structure. Previous works reported that the most important microstructural parameters, affecting the strength of pearlitic steel most, are generally the thickness, shape and orientation of a cementite, and interlamellar spacing or the distance between cementite bands in a laminated structure of pearlitic steel wires.
Although there have been many works on finding the relation between the microstructure of a pearlitic steel and its mechanical properties in a drawn pearlitic steel wire, no works has been reported on the micro deformation of cementite band during wire drawing of pearlitic steel. In general, a wire drawing process changes not only the orientation of cementite but also its shape and dimension. In high carbon steels, the decrease of interlamellar spacing causes the reduction of cementite thickness. In order to control the strength of drawn pearlitic steel wire, it is necessary to trace the microstructural evolutions, such as micro deformation of a cementite band, during wire drawing.
The current author proposed a new simulation model, which can predict the micro-deformation behaviors of cementite bands using a finite element analysis in a micro scale. In his simulation model, a macro-deformation behavior at a material point during macro wire drawing of pearlitic steel could be represented by an averaged response of a unit problem. The material behavior in this unit model is assumed as rigid viscoplastic. Then, the unit model problem could be completed by defining the boundary conditions based on the macro velocity gradient that is obtained by performing the macro finite element simulation for wire drawing. Micro structural deformation of a cementite band would be predicted by micro finite element simulations with the above unit problem. Eventually, effects of various parameters such as the orientation and location of cementite on its micro deformation behaviors are studied.