Tamamlanmış Proje


This extensive research program on brake noise vibration and harshness (Brake NVH) covers research topics ranging from noise generation mechanisms for such common BNVH problems as squeal, creep groan, and judder as well as development of measurement techniques to characterize friction materials to investigate their propensity to cause brake noise. Research in this laboratory has resulted in numerous discoveries that led to several publications and patents.

In its simplest form, an automobile brake may be considered as a rotating disk with two pads mounted on either side inside a caliper. When hydraulic pressure is applied, the pads contact the rotating disk and decelerate it by means of friction. Brakes are designed to dissipate kinetic energy into heat. However, some of the kinetic energy goes into vibrations of the brake and caliper (and sometimes the suspension). In the case of aircraft brakes, stacks of annular disks are squeezed together to stop the rotors attached to the wheel.

The observed dynamic responses of brakes range from resonant excitation of any combination of vibration modes to instabilities. Such different vibration responses are associated with different design, operating, and environmental conditions. Lack of repeatability of vibration responses, even under seemingly identical operating conditions, is a common characteristic of brakes and other friction-excited dynamic systems. Observations suggest that dynamic response characteristics of friction-excited systems, such as brakes, are very sensitive to the environment, such as humidity, and to operating parameters such as normal pressure. A small change in normal pressure can lead to a change of the vibration response from one that is harmonic to one that is chaotic.

Brake Noise and Vibration Research


  • A. Akay (2021). "Noise Control Engineering and Education", The Bridge, v.51(2) p.13-18, Full Text
  • A. Akay, G. G. Fleming, R.D. Hellweg, G. C. Maling, Jr., and E. W. Wood (Eds.) (2020). "Engineering a Quieter America: Noise Control Engineering Education", Technology for a Quieter America (ISBN: 978-1-7325986-3-8), Full Text
  • A. Akay, G. G. Fleming, R.D. Hellweg, G. C. Maling, Jr., and E. W. Wood (Eds.) (2020). "UAS and UAV (Drone) Noise Emissions and Noise Control Engineering Technology: Workshop Final Report", Technology for a Quieter America (ISBN: 978-1-7325986-2-1), Full Text
  • A. Akay, (2018) "Bilkent University: A World-Class Academic Community," in Bilkent: Thirty Years in Historical Perspective, Full Text
  • A. Akay, G. G. Fleming, R.D. Hellweg, G. C. Maling, Jr., and E. W. Wood (Eds.) (2017). "Commercial Aviation: A New Era", Engineering a Quieter America (ISBN: 978-0-9899431-9-2)
  • A. Akay and A. Carcaterra (2014). "Damping Mechanisms," (Active and Passive Vibration Control of Structures, Hagedorn P., Spelsberg-Korspeter G., Eds., CISM International Centre for Mechanical Sciences) Spr p.259 – 299.
  • A. Carcaterra and A. Akay (2016). "Fluctuation-dissipation and energy properties of a finite bath", Physical Review E, v.93 p.032142
  • Roveri, N., Carcaterra, A., Akay, A. (2014). "Frequency intermittency and energy pumping by linear attachments", Journal of Sound and Vibration, v.333 p.4281-4294
  • Akay, A., Carcaterra, A., Bernardini, C. (2012). "Trapping of vibration energy into a set of resonators: Theory and application to aerospace structures", Mechanical Systems and Signal Processing, v.26 p.1
  • Carcaterra, A., Akay, A. (2011). "Dissipation in a finite-size bath", Physical Review E, v.84 p.011121
  • Fagiani, R., Massi, F., Chatelet, E., Berthier, Y., Akay, A. (2011). "Tactile perception by friction induced vibrations", Tribology International, v.44 p.1100
  • Pierce, A., Akay, A. (2009). "Intrinsic damping models and their role in predicting structural response", Journal of the Acoustical Society of America, v.125 p.2602
  • Carcaterra, A., Akay, A. (2009). "Vibration absorption based on cluster of beams", J. Sound and Vibration
  • Akay, A., Giannini, O., Massi, F., Sestieri, A. (2009). "Disc brake squeal characterization through simplified test rigs", Mechanical Systems and Signal Processing, v.23 p.2590-2607
  • N. Roveri,, A. Carcaterra,, Akay, A. (2009). "Vibration absorption using non-dissipative complex attachments with impacts and parametric stiffness", Journal of the Acoustical Society of America, v.126 p.2306-2314
  • N. Roveri,, A. Carcaterra,, Akay, A. (2009). "Energy equipartition and frequency distribution in complex attachments", Journal of the Acoustical Society of America, v.126 p.122-128
  • Tangpong, X., Wickert, J., Akay, A. (2008). "Finite Element Model for Hysteretic Friction Damping of Traveling Wave Vibration in Axisymmetric Structures", ASME Journal of Vibration and Acoustics, v.130
  • Tangpong, X., Wickert, J., Akay, A. (2008). "Distributed friction damping of traveling wave vibration in rods", Philosophical Transactions of the Royal Society: Part A, v.366 p.811-827
  • Akay, A. (2008). "A Renaissance in Engineering PhD Education", European Journal of Engineering Education, v.33 p.403-413
  • Akay, A., Carcaterra, A., Lenti, F. (2007). "Pseudo-Damping in Undamped Plates and Shells", J. Acoust. Soc. Amer, v.122 p.804-813
  • Carcaterra, A., Akay, A. (2007). "Theoretical Foundations of Apparent-Damping Phenomena and Nearly Irreversible Energy Exchange in Linear Conservative Systems", Journal of the Acoustical Society of America, v.121 p.1971-1982
  • Ding, J., Tsaur, F., Lips, A., Akay, A. (2007). "Acoustical observation of bubble oscillations induced by bubble popping", Physical Review E, v.75
  • Carcaterra, A., Akay, A., Koc, I.M. (2006). "Near-irreversibility in a conservative linear structure with singularity points in its modal density", J. Acoust. Soc. Amer, v.119 p.2141-2149
  • Giannini, O., Akay, A., Massi, F. (2006). "Experimental analysis of brake squeal noise on a laboratory brake setup", J. Sound Vibration, v.292 p.1-20
  • Koh, K., Griffin, J.H., Filippi, S., Akay, A. (2005). "Characterization of turbine blade friction dampers", J. Engineering for Gas Turbines and Power, v.127 p.856-862
  • Akay, A., Carcaterra, A., Xu, Z., Koc, I. (2005). "Experiment on vibration absorption using energy sinks", Journal of the Acoustical Society of America, v.118 p.3043-3049
  • Koc, I., Carcaterra, A., Xu, Z., Akay, A. (2005). "Energy Sinks for Vibration Reduction: Optimum Frequency Distribution", Journal of the Acoustical Society of America, v.118 p.3031-3042
  • Carcaterra, A., Akay, A. (2004). "Transient Energy Exchange Between a Primary Structure and a Set of Oscillators: Return Time and Apparent Damping", Journal of the Acoustical Society of America, v.115 p.683-696
  • Filippi, S., Akay, A., Gola, M. (2004). "Measurement of Tangential Contact Hysteresis During Microslip", ASME Journal of Tribology, v.126 p.482-489
  • Akay, A. (2003). "The renaissance engineer: Educating engineers in a post-9/11 world", European Journal of Engineering Education, v.28 p.145-150
  • Karpenko, Y., Akay, A. (2002). "A numerical method for analysis of extended rough wavy surfaces in contact", ASME J. Tribology, v.124 p.668-679
  • Akay, A. (2002). "Acoustics of Friction", J. Acoust. Soc. Amer., v.111 p.1525-1548
  • Karpenko, Y., Akay, A. (2001). "A numerical model of friction between rough surfaces", Tribology International, v.34 p.531-545
  • Çelik, C., Akay, A. (2000). "Dissipation in solids: Thermal oscillations of atoms", J. Acoust. Soc. Amer, v.108(1) p.184-191
  • Bengisu, M.T., Akay, A. (1999). "Stick-slip oscillations: Dynamics of friction and surface roughness", J. Acoust. Soc. Amer., v.105(1) p.194-205
  • Tzou, K., Wickert, J.A., Akay, A. (1998). "In-plane vibration modes of arbitrarily thick disks", ASME J. Vibration and Acoustics, v.120 p.384-391
  • Akay, A., Xu, Z. (1998). "Experiments on acoustic streaming in a fluid layer between vibrating surfaces and amplitude-dependent damping of vibrations", J. Acoust Soc. Amer., v.103 p.865-871
  • Tzou, K., Wickert, J.A., Akay, A. (1998). "Frequency clusters in the spectrum of annular cylinders", J. Applied Mechanics, v.65(4) p.797-803
  • Bengisu, M.T., Akay, A. (1997). "Relation of dry friction to surface roughness", ASME J. Tribology, v.119 p.18-25
  • Rhee, J., Akay, A. (1996). "Dynamic response of a revolute joint with clearance", Mechanism and Machine Theory, v.31 p.121-134
  • Kang, J., Akay, A., Xu, Z. (1995). "Intertia effects on compressible squeeze films", ASME J. Vibrations and Acoustics, v.117 p.94-102
  • Bengisu, M.T., Akay, A. (1994). "Stability of friction-induced vibrations in multi-degree-of-freedom systems", J. Sound and Vibration, v.171 p.557-570
  • Swayze, J., Akay, A. (1994). "Effects of system dynamics on friction-induced oscillations", J. Sound and Vibration, v.173 p.599-609
  • Gaunaurd, G.C., Akay, A. (1994). "Isolation of the 'spectrograms' and 'rosettes' of insonified sets of submerged, concentric, thin shells", ASME J. Vibration and Acoustics, v.116 p.573-577
  • Akay, A., Ingard, K.U. (1993). "Radiation from bending waves in the presence of a flow boundary layer", ASME J. Vibration and Acoustics, v.115 p.411-416
  • Uras, H., Akay, A. (1993). "Mechanical engineering capstone design course", J. Mechanical Engineering Education, v.21 p.347-354
  • Akay, A., Sener, S., Gaunaurd, G.C. (1993). "Acoustic scattering from fluid-filled, concentric, submerged, cylindrical elastic shells", J. Acoustical Society of America, v.94 p.3277-3294
  • Wu, X.F., Akay, A. (1992). "Sound radiation from vibrating bodies in motion", J. Acoust. Soc. Amer., v.91 p.2544-2555
  • Latcha, M., Akay, A. (1992). "Effects of viscous and thermal losses on radiation from an infinite plate", ASME J. Vibration and Acoustics, v.114 p.415-419
  • Akay, A. (1992). "Normal and angular motions at rough planar contacts during sliding with friction- Discussion", ASME J. Tribology, v.114 p.578
  • Akay, A. (1991). "Scattering of sound from concentric cylindrical shells", J. Acoust. Soc. Amer., v.89 p.1572-1578
  • Onsay, T., Akay, A. (1991). "Vibration reduction of a flexible arm by time-optimal open-loop control", J. Sound and Vibration, v.147 p.283-300
  • Akay, A. (1990). "Radiation from a finite array of simple sources", J. Acoust. Soc. Amer., v.87 p.1449-1454
  • Ingrad, K.U., Akay, A. (1987). "Acoustic radiation from bending waves of a plate", J. Vibrations, Acoustics, Stress and Reliability in Design, v.109 p.75-81
  • Ingrad, K.U., Akay, A. (1987). "On the vibration damping of a plate by means of a viscous fluid layer", J. Vibration, Acoustics, Stress and Reliability in Design, v.109 p.178-184
  • Bengisu, M.T., Hidayetoglu, T., Akay, A. (1986). "A theoretical and experimental investigation of contact loss in the clearances of a four-bar mechanism", J. Mechanism, Transmission, and Automation in Design, v.108 p.237-244
  • Latcha, M., Akay, A. (1986). "Application of the Helmholtz integral in acoustics", J. Vibration, Acoustics, Stress and Reliability in Design, v.108 p.447-453
  • Akay, A., Tokunage, M., Latcha, M. (1984). "A theoretical analysis of transient sound radiation from a clamped circular plate", J. Applied Mechanics, v.51 p.41-47
  • Akay, A., Bengisu, M.T., Latcha, M. (1983). "Transient acoustic radiation from impacted beam-like structures", J. Sound and Vibration, v.91 p.135-145
  • Akay, A., Latcha, M. (1983). "Sound radiation from an impact-excited clamped circular plate in an infinite baffle", J. Acoust. Soc. Amer, v.74 p.640-648
  • Akay, A. (1982). "Mathematical modeling of transient vibration and acoustic radiation from impacted systems", J. Mathematical Modeling, v.3 p.535-541
  • Cook, R., Hamm, C.W., Akay, A. (1981). "Shock measurement with noncontacting fiber optic levers", J. Sound and Vibration, v.76 p.443-456
  • Salt, N., Konishi, T., Cook, R., Akay, A. (1981). "Comparison between the effects of continuous and impact noise on cochlear potentials of guinea pigs", J. Acoust. Soc. Amer., v.69 p.1746-1752
  • Akay, A., T. H. Hodgson (1978). "Sound radiation from a accelerated or decelerated sphere", J. Acoust. Soc. Amer., v.63 p.313-318
  • Akay, A., T. H. Hodgson (1978). "Acoustic radiation from the elastic impact of a sphere with a slab", Applied Acoustics, v.11 p.285-304
  • Akay, A., E. Saibel (1978). "Fracture time of composites under tensile loading", J. Composite Materials, v.12 p.262-274
  • Akay, A. (1978). "A review of impact noise", J. Acoust. Soc. Amer, v.64 p.977-987
  • Akay, A., E. Saibel (1976). "Fracture of polymeric materials under tensile loads", Wear, v.37 p.377-381