Prepared By :• Mustafa ERARSLAN• Serkan Ahmet ÇAM• Osman KAYA• Ferhat AYDIN• Ahmet KOYUNCU• Kadir YÜZER
Sound is a sequence of waves ofpressure that propagates throughcompressible media such as air,water orsolids. During propagation, waves can bereflected, refracted, or attenuated by themedium.
The mechanical vibrations that can beinterpreted as sound are able to travelthrough all forms of matter: gases, liquids,solids, and plasmas. The matter thatsupports the sound is called the medium.Sound cannot travel through a vacuum.
• Frequency, or its inverse, the period• Wavelength• Wavenumber• Amplitude• Sound pressure• Sound intensity• Speed of sound• Direction• Polarization (Transverse Waves)
Ultrasound is cyclic sound pressure with a frequency greaterthan the upper limit of human hearing. Ultrasound is thus not separatedfrom "normal" (audible) sound based on differences in physicalproperties, only the fact that humans cannot hear it. Although this limitvaries from person to person, it is approximately 20 kilohertz (20,000hertz) in healthy, young adults. The production of ultrasound is used inmany different fields, typically to penetrate a medium and measure thereflection signature or supply focused energy. The reflection signaturecan reveal details about the inner structure of the medium, a propertyalso used by animals such as bats for hunting. The most well knownapplication of ultrasound is its use in sonography to produce pictures offetuses in the human womb. There are a vast number of otherapplications as well.
Infrasound is sound that is lower in frequency than 20 Hz(Hertz) or cycles per second, the "normal" limit of human hearing.Hearing becomes gradually less sensitive as frequency decreases, sofor humans to perceive infrasound, the sound pressure must besufficiently high. The ear is the primary organ for sensing infrasound,but at higher levels it is possible to feel infrasound vibrations invarious parts of the body. The study of such sound waves is sometimes referred to asinfrasonics, covering sounds beneath 20 Hz down to 0.001 Hz. Thisfrequency range is utilized for monitoring earthquakes, charting rockand petroleum formations below the earth, and also inballistocardiography and seismocardiography to study the mechanicsof the heart. Infrasound is characterized by an ability to cover longdistances and get around obstacles with little dissipation.
Acoustics is the interdisciplinary science that deals with thestudy of all mechanical waves in gases, liquids, and solids includingvibration, sound, ultrasound and infrasound. A scientist who works inthe field of acoustics is an acoustician while someone working in thefield of acoustics technology may be called an acoustical engineer. Theapplication of acoustics can be seen in almost all aspects of modernsociety with the most obvious being the audio and noise controlindustries. Hearing is one of the most crucial means of survival in theanimal world, and speech is one of the most distinctive characteristicsof human development and culture. So it is no surprise that the scienceof acoustics spreads across so many facets of our society—music,medicine, architecture, industrial production, warfare and more. Art,craft, science and technology have provoked one another to advancethe whole, as in many other fields of knowledge.
For Subsonic ; where: M = is Mach number qc = is impact pressure (diffrence between total pressure and static pressure) p = is static pressure γ = is the ratio of specific heat of a gas at a constant pressure to heat at a constant volume (1.4 for air). High-Regime Subsonic Transonic Sonic Supersonic Hypersonic hypersonicMach <1.0 0.8–1.2 1.0 1.2–5.0 5.0–10.0 >10.0
For Supersonic ;For air Simplified Formula is ;
Spectrum of soundFrequency range Description Example Hz 0 - 20 Infrasound Earth quake Audible 20 - 20.000 Speech, music sound > 20.000 Ultrasound
Atomic structures gas liquid solid•low density •medium density•weak bonding forces •medium bonding •high density forces •strong bonding forces •crystallographic structure
Wave propagation Longitudinal waves propagate in all kind of materials. Transverse waves only propagate in solid bodies. Due to the different type of oscillation, transverse waves travel at lower speeds.Sound velocity mainly depends on the density and E-modulus of the material. 330 m/s Air Water 1480 m/sSteel, long 5920 m/sSteel, trans 3250 m/s
Reflection and Transmission• As soon as a sound wave comes to a change in material characteristics ,e.g. the surface of a workpiece, or an internal inclusion, wave propagation will change too:
Behaviour at an interface Medium 1 Medium 2Incoming wave Transmitted waveReflected wave Interface
Sound wave with frequency f U(f)An alternating voltage generates crystal oscillations at the frequency f
Reception of ultrasonic wavesA sound wave hitting a piezoelectric crystal, inducescrystal vibration which then causes electrical voltagesat the crystal surfaces. Electrical Piezoelectrical Ultrasonic wave energy crystal
amplifier screen IP horizontal BE sweep clock pulserprobe work piece
Sound reflection at a flaw sProbe Sound travel path Flaw Work piece
Plate testing IP BE F delamination 0 2 4 6 8 10plate IP = Initial pulse F = Flaw BE = Backwall echo
Wall thickness measurement ss s Corrosion 0 2 4 6 8 10
Through transmission testing Through transmission signal1 T R 12 T R 2 0 2 4 6 8 10 Flaw
Immersion testing 1 2 surface = water delaysound entry backwall flaw IP 1 IP 2 IE IE BE BE F 0 2 4 6 8 10 0 2 4 6 8 10
Weld inspection ß = probe angle a = s sinß s = sound path F a = surface distance a = a - x a‘ = reduced surface distance s d = s cosß d‘= virtual depth d = actual depth0 20 40 60 80 100 T= material thickness d = 2T - t a x a ß d Lack of fusionWork piece with welding s
Straight beam inspection techniques: Direct contact, Direct contact, Fixed delaysingle element probe dual element probeThrough transmission Immersion testing
• Sonar stands for sound navigation and ranging.• Sonar uses a beam of sound waves and directs them downward.• After the sound wave hits the bottom of the ocean (ocean floor), or an object, it will bounce off and return back causing an echo.• This is then recorded on a depth recorder on the ship.• Some marine organisms use Echolocation, which is a form of sonar (dolphins, whales, porpoises).
Active Passive• Deploys and receives its • Listening device own signal • Detects underwater• Two categories echo sounds ranging, and • Belongs to the Direct communication Listening category• Allied Submarine Detection Investigation Committee ( ASDICS)
Active Passive• Transducer • Transducer (Only Receiver) (Emitter/Receiver) • Indicator• Indicator • Recorder• Recorder • Computer System• Computer System
Diagnostic sonography (ultrasonography) is an ultrasound-based diagnostic imaging technique used for visualizingsubcutaneous body structures including tendons, muscles, joints,vessels and internal organs for possible pathology or lesions.Obstetric sonography is commonly used during pregnancy and iswidely recognized by the public. In physics, the term "ultrasound" applies to all sound waveswith a frequency above the audible range of human hearing, about20,000 Hz. The frequencies used in diagnostic ultrasound aretypically between 2 and 18 MHz.