Keynote Speaker 1
Biography
Ihsan Efeoglu is a professor of Mechanical Engineering at Atatürk University in Turkey. His work has centered in surface Engineering around plasma-based technologies. His activity is focuses on the development and in the structural-mechanical-tribological-chemical characterization of functional coatings. He has 25 years of field experience in Magnetron sputtering-PVD fields, using pulsed-dc and HiPIMS technology with CFUBMS PVD system.
Title: Synthesis of Nb and Zr Added TiCN:TiBN Composite Coatings with CFUBM-HiPIMS Technology and Investigation of Mechanical Properties
Abstract:
High-power impulse magnetron sputtering (HIPIMS) was introduced in the late 1990s as a unique physical vapor deposition method. In the early 2000s, it started to show itself in R&D studies with the technological developments in electronic power designs for HiPIMS technology. Today, HiPIMS is integrated and successfully used in magnetic field sputtering systems on an industrial scale. HiPIMS technology provides a stable and uniform discharge plasma formation with high current density, especially ensuring that the adhesion bond between the coating film and the base material is strong.
Single or multiple coatings of transition metals with C-B-N have many advantages; these are high hardness, adhesion, and wear, while low oxidation and corrosion resistance. Functional properties can be achieved by adding certain amounts of different transition elements (Ti, Zr, Nb etc.) to carbon-boron nitride-based coatings. In this study, mechanical properties were investigated by adding Zr and Nb transition elements to TiCN:TiBN composite-graded coatings using the CFUBMS-HiPIMS hybrid system as a PVD method. Coatings were synthesized on 4140 tool steel and silicon wafer using Taguchi experimental design. While the TiCN:TiBN graded composite structure was synthesized with Cr, Ti, TiB2 targets integrated in the CFUBMS-HiPIMS system, Nb and Zr were used as the fourth target material, respectively. While the mechanical properties (hardness and adhesion) of the coatings synthesized on 4140 steel were investigated, the microstructural properties were analyzed on Si wafer. 100-200 nm thick Cr transition layer was grown as an intermediate layer to increase the adhesion. It was observed that the adhesion changed as a function of the negative voltage applied to the Zr and Nb targets. In the case of Nb addition, it was determined that the highest critical load values (Lc: 90-100N) were reached at -800V, while when Zr was added, it was observed that the adhesion value appeared at lower levels (Lc: 50-60N).
Keynote Speaker 2
Prof. Mohd Nasir Tamin earned his doctoral degree in Mechanical Engineering and Applied Mechanics from the University of Rhode Island, USA in 1997. He has been with the School of Mechanical Engineering, Universiti Teknologi Malaysia since 1984. Prof. Nasir’s research team activities focus on the development of constitutive and damage models for ductile metals and fibrous composite laminates.
He leads his research team on few successful research collaborations with industries including Intel Technology on the development of a validated methodology for reliability prediction of microelectronic BGA packages and through-silicon via (TSV) interconnects, with Kiswire (Korea) for fatigue life improvement of steel wire ropes, and with Airbus and Aerospace Malaysia Innovation Center (AMIC) for damage detection in FRP composite laminates using the digital image correlation technique (DIC).
Prof. Nasir has been invited as a visiting researcher at Sophia University, Tokyo (Japan), a visiting professor at the Institut Supérieur de l’Automobile et des Transport, (ISAT), Nevers, France, Dongguk University, Seoul, Korea, and as a visiting research professor at the University of Southampton (Malaysia Campus). He is keen in promoting the university-industry collaboration, and the academic and research collaboration among colleagues across the globe.
Title: Characterization of Multifractal Fatigue Crack Propagation
Abstract:
Advanced load-bearing structures such as aircraft spoiler and fuselage, helicopter rotor blade, marine propellers and ship hull operate under fluctuating loads. Damage tolerant design of these structures requires continuous monitoring of existing crack to ensure the structural integrity and safety. For this purpose, the fracture mechanics approach determines the rate of crack propagation and estimates the time for the crack to reach the critical length prior to catastrophic fracture. This requires the determination of the stress intensity factor range, quantified in terms of applied stress range, crack length and crack geometry, to quantify the driving force of the crack tip. The crack geometry factor is available for standard test specimens and structures with relatively simple geometry. However, the stress intensity factor range could also be estimated computationally using the finite element (FE) method. The absence of the much-needed geometry factor of numerous advanced engineering structures renders the fracture mechanics equation inapplicable for calculating the crack-tip driving force. Fortunately, a propagating crack inherits the self-similar and multi-scale fractal features along the length and surfaces of the crack wake. The fractality of the fatigue crack is quantified in terms of their fractal dimensions, and unique relationship is established with the stress intensity factor range. This, in turn, eliminates the need for the crack geometry factor in determining the fatigue crack propagation of the material.
This paper/talk discusses the methodology to quantify the fractality of a fatigue crack of AISI 410 martensitic stainless steel. Fractal analysis of microscopic images along the edge length of the crack is performed using the Box-counting method. Fatigue crack growth tests on C(T) specimen establish the reference crack growth rate response of the alloy. Results show that the crack initially exhibits a Euclidean nature (dF ≈ 1). The fractal dimension increases steadily with increasing crack length in the Paris crack growth rate region with 1.05 < dF < 1.24. The corresponding stress intensity factor range varies between 18 ≤ ∆KI ≤ 40 MPa√m. The fractal dimension, dF correlates linearly with the normalized stress intensity factor range, within the Paris crack growth region. This enables the multifractal fatigue crack propagation rate of the material to be determined using the fracture mechanics equation, but without requiring the geometry factor of the crack.