Engineering

ENGINEERING SERVICE
Noise and Vibration Simulation, Measurement & Countermeasures of Ships and Offshore Structures

  • Vibration and noise of ships and offshore structures reduce habitability and comforts of passengers and crew leading to a reduction in their work efficiency. In addition, excessive vibration can cause malfunction or damage of onboard equipment and fatigue damages of structures. Moreover, underwater-radiated noise (URN) has adverse effect upon the marine wildlife fauna by noise pollution as well as stealth performance of naval vessels. Hence, vibration and noise are the most important performance factors to get recognition as high-quality ships and offshore structures.
  • Vibration and noise of ships and offshore structures are induced by onboard machinery (especially the main engine and propeller), fluid movement in the cargo holds and pipes, and ocean environment. They are normally assessed according to the contract specifications between the owner and the builder, and governed by the relevant IMO codes, classification rules, standards of ISO, laws of relevant nations and so forth.
  • If excessive vibration or noise of ships and offshore structures is found during the sea trials, it must be rectified using some countermeasures. However, such work is normally cost-expensive and time-consuming, and in the worst cases, can result the delivery delay. Thus, prevention of vibration and noise during design and construction stages is more cost-efficient and effective than remedial measures after their construction.
  • The design and construction of low-noisy and low-vibratory ships and offshore structures can be done by review on basic designs, empirical and precise engineering analysis and evaluation on their performance, and optimal measures for expected troublesome vibration and noise during their design and construction stages if any.
  • Our company has successfully provided engineering consulting service to evaluate and mitigate noise and vibration of ships and offshore structures for major shipbuilding and ship design companies in Korea, China and Japan since 2000. The consulting service based on our own advanced simulation and field measurement technology is provided from initial design stage to sea trials as followings:
    • Item Initial Design Stage Detail Design Stage Construction Sea Trial
    Vibration ▪ Design review
    ▪ Empirical formula to estimate natural frequencies
    ▪ Source identification
    ▪ Recommendation
    		 ▪ Numerical modeling
    ▪ Global & local vibration analysis(FEM & others)
    ▪ Evaluation
    ▪ Recommendation if necessary    		 ▪ FAT on major sources
    ▪ Structural dynamic test in yard
    ▪ Countermeasures if necessary    		 ▪ Vibration measurement
    ▪ Identification of troublesome sources if any
    ▪ Optimal countermeasures if necessary
    Onboard noise & Underwater-radiated noise ▪ Design review
    ▪ Source identification
    ▪ Budgeting source levels
    ▪ Recommendation    		 ▪ Numerical modeling (Structure, HVAC, Foundation, etc.)
    ▪ Foundation impedance analysis
    ▪ Airborne-, Structure-borne, HVAC noise analysis
    ▪ Recommendation if necessary
    		 ▪ FAT on major sources
    ▪ Acoustic performance measurement of structures & fittings
    ▪ Comparison between prediction and measurement
    ▪ Countermeasures if necessary    		 ▪ Onboard noise, URN measurement
    ▪ Identification of troublesome sources if any
    ▪ Optimal countermeasures if necessary
  • All the modeling and simulation on noise and vibration are done by advanced authentic and precise methods utilizing not only general purpose simulation S/W but also our own in-house S/W developed by ourselves based on advanced methods as followings:
    • Item Analysis Methods
    Vibration  
    Onboard noise & Underwater-radiated noise ▪ Indoor airborne noise : Diffuse field theory, Triangular beam tracing method
    ▪ Outdoor airborne noise : ISO 9613-2, Diffuse field theory
    ▪ Structure-borne noise : Statistical Energy Analysis(SEA)
    ▪ HVAC noise : NEBB(USA) method
    ▪ Foundation impedance : FEM
    ▪ URN : FEM, SEA, Transfer function method
  • Moreover, our company has almost all kind of instruments to measure and analyze multi-channel noise and vibration signals to confirm real responses and to identify troublesome source identification whose information is utilized to provide optimal countermeasures.
    • Equipment Uses Type Quan
    B&K PULSE Signal Analyzer Platform Real time signal measurement & storage signal Analysis 16Ch.B&K PULSE 3560D 1
    12Ch. B&K PULSE 3053-B-120 1
    4Ch. Bamp;&K PULSE 3560C 1
    2Ch. B&K 2144 1
    2Ch. B&K 3550 1
    Portable Dynamic Signal Analyzer(4 Channel) FFT spectrum analysis, order tracking, octave spectrum analysis and data recorder BENSTONE Impaq Elite 2
    Sound Level Meter Portable sound analyzer B&K2250 1
    B&K2260 1
    Vibration Exciter Modal excitation B&K4808/4812 2
    Tapping Machine Impact sound generator B&K3207 1
    Impulse Sledge Hammer Modal & structural analysis (excitation hammer for structures with a definable impulse force) Low range frequency / DYTRAN 5803A 1
    Middle range frequency / DYTRAN 5802A 1
    High range frequency / DYTRAN 5800B 1
    Omni-Source Loudspeaker Omni-directional sound source B&K4296 1
    Torsional Vibration Measurement System Torsional Vibration measurement of propulsion shaft TorqueTrak10K 1
    Telemetry system 1
    Gap Sensor Non-contact disp. measurement AEC 37MS-30 1
    Impedance Tube Kit Acoustic property measurement of materials B&K4206 1
    Rotating Microphone Boom Building acoustic measurement B&K3923 1
    Microphone Sound pressure measurement B&K4166/4189/4190 12
    Surface Microphone Surface pressure measurement B&K4949 2
    Hydrophone Underwater radiation noise generation and measurement B&K8104 2
    Accelerometer Vibration/Shock measurement DYTRAN 3148D 30
    Endevco 65-100-Y(3-axis) 1
    B&K4397A 2
    B&K4371/4382/4393/ 8000 7
    WILCOXON 731A 1
    Calibration Exciter Calibration for accelerometer PCB 699A02 1
    Sound Level Calibrator Calibration for sound level meter MICROTECH GEFELL 4000 CI 1
    Climate Measuring Instrument Temperature / Humidity / Volume flow velocity / Differential pressure / Illumination measurement TESTO480 1
    Humidity/Temp. Monitor Humidity & Temp. measurement MHT-381SD 9
    Illumination Measurement Lux Measurement 3423 LUX HITESTER 1
    Digital Clamp MeterInsulation Tester Electric current / Voltage / Resistance measurement KYORITRU 2007A SAEHAN SH-2000M 1