M.R. Myers¹, A.B. Jorge², D.E. Yuhas³, D.G. Walker¹

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.3, pp. 221-248, 2012, DOI:10.3970/cmes.2012.083.221

Abstract An adaptive extended Kalman filter is developed and investigated for a transient heat transfer problem in which a high heat flux spot source is applied on one side of a thin plate and ultrasonic pulse time of flight is measured between spatially separated transducers on the opposite side of the plate. The novel approach is based on the uncertainty in the state model covariance and leverages trends in the extended Kalman filter covariance to drive changes to the state model covariance during convergence. This work is an integral part of an effort to develop a… More >

Younho Cho, Weibin Li, Bin Yang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.2, pp. 49-50, 2011, DOI:10.3970/icces.2011.017.049

Abstract This paper aims at an experimental method for detecting thermal-damages in a tube-like structure using acoustic nonlinear parameter of ultrasonic guided waves. The material nonlinearity of aluminum pipe specimens, which have been subjected to different heat-loading cycles, is measured to characterize the micro-damages. Flexible Polyvinylidene Fluoride (PVDF) comb transducers are used to generate and receive the fundamental and second harmonic waves. The amplitude of the second harmonic wave is extracted from the Fast Fourier Transform (FFT) spectrum of a received signal. The measured relative nonlinear parameter increases monotonically as a function of the propagation distance, More >

R. Muhammad*, A. Maurotto, M. Demiral, A. Roy and V.V. Silberschmidt

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.3, pp. 95-96, 2011, DOI:10.3970/icces.2011.019.095

Abstract Analysis of the cutting process in machining of modern engineering materials (Ti- and Ni-based alloys), which are hard-to-cut materials, is a challenge that needs to be addressed. Machining of these alloys with conventional techniques is difficult and often results in tool failure due to the high cutting forces imposed on the tool. In a machining operation, cutting forces causes severe deformations in the proximity of the cutting edge, producing high stresses, strain, strain-rates and temperatures in the workpiece.
Ultrasonically assisted turning (UAT) is an advanced machining process, which has shown several advantages especially in the… More >

Q. Chen, K. Kariya

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.1, pp. 3-4, 2011, DOI:10.3970/icces.2011.016.003

Abstract Abstract Al alloys have been widely used as engineering materials in many machines and structures because of their excellent properties such as high specific strength, high resistance to corrosion and easy to recycle. Especially, high strength Al alloys are effective to reduce environment load through achieving low fuel consumption in automobile engines. On the other hand, high strength Al alloys have no definite fatigue limit and their fatigue strengths are very low in comparison with their high static strengths. It is important to know the fatigue strength of high strength Al alloys in the long… More >

Yoshiyuki Furuya

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.1, pp. 1-2, 2011, DOI:10.3970/icces.2011.016.001

Abstract Gigacycle fatigue takes place in high-strength steel. In this case, fish-eye fracture eliminates a conventional fatigue limit. This means that the fish-eye fracture is a key to understand the gigacycle fatigue of high-strength steel. Evaluation of gigacycle fatigue properties needs accelerated fatigue testing since gigacycle fatigue tests take long time. For example, a 10⁹-cycles fatigue test takes more than 3 months at conventional 100 Hz. For this acceleration, ultrasonic fatigue testing is a very powerful tool since it achieves 20 kHz and completes the 10⁹-cycles in a day. However, frequency effects must sufficiently be investigated before… More >

L. Zhang¹, T. Boulet¹, J. Hein¹, M. Arnoult¹, M. Negahban¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.15, No.2, pp. 37-46, 2010, DOI:10.3970/icces.2010.015.037

Abstract The modeling of the response of the human head to blast like loading is of importance for many applications including the study of traumatic brain injury resulting from improvised explosive devices. One key issue in simulating the response of the head is to have models that are characteristic of the response of the head and its components under these conditions. We review different characterization efforts for evaluating the response of the skin, skull, and brain within this window of response and use these results to develop models appropriate for the characterization of each component. We More >

Brad Regez¹, Sridhar Krishnaswamy¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.4, pp. 111-112, 2009, DOI:10.3970/icces.2009.012.111

Abstract Ultrasonic inspection techniques have a proven record of applications during manufacturing and maintenance of metallic and composite aircraft structures. Traditional ultrasonic inspection techniques use a point-by-point scanning method to acquire a full-field image. This scanning method is slow and inadequate in satisfying modern manufacturing and maintenance time line requirements. The next generation of ultrasonic inspection eliminates the need for point-by-point scanning using an imaging array that is capable of displaying thousands of points to create a full-field image in real-time.
In this study, a next generation dual-channel ultrasonic imaging system is used for real-time three-dimensional evaluation… More >

Kuen Ming Shu¹, Chien Chih Chen²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.4, pp. 109-110, 2009, DOI:10.3970/icces.2009.011.109

Abstract Ultrasonic welding is the joining or reforming of thermoplastics through the use of heat generated from high-frequency mechanical motion. Rotary welding is a technique to press two parts together and one part is hold fixed the other rotates at high speed, the friction between the two parts generate heat which causes the parts to melt at the interface, when rotation stops, the weld cools down and solidifies. In this research, an experimental set-up integrated these two different welding processes in one machine set was designed and fabricated to provide a tool to study the integrated More >

C.C. Chia¹, S.G. Jang¹, J.R. Lee², D.J. Yoon²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.2, pp. 29-30, 2009, DOI:10.3970/icces.2009.011.029

Abstract An ultrasonic propagation imaging (UPI) system consisted of a Q-switched Nd-YAG pulsed laser with 20 Hz-repetition rate and a motorized tilting mirror system for rapid scanning of target was developed. The system which requires neither reference data nor fixed focal length could be used for health monitoring of curved structures. If combined with a fiber acoustic wave PZT (FAWPZT) sensor, it could be used to perform inspection on hot target structures, which present formidable challenges to the usage of contact piezoelectric transducers mainly due to the Curie temperature limitation of transducers and debonding problem due… More >

G.V. Norton^*, J.C. Novarini^†

Molecular & Cellular Biomechanics, Vol.4, No.2, pp. 75-86, 2007, DOI:10.3970/mcb.2007.004.075

Abstract Ultrasonic imaging in medical applications involves propagation and scattering of acoustic waves within and by biological tissues that are intrinsically dispersive. Analytical approaches for modeling propagation and scattering in inhomogeneous media are difficult and often require extremely simplifying approximations in order to achieve a solution. To avoid such approximations, the direct numerical solution of the wave equation via the method of finite differences offers the most direct tool, which takes into account diffraction and refraction. It also allows for detailed modeling of the real anatomic structure and combination/layering of tissues. In all cases the correct… More >