ISO 18312-1:2012

Overview

ISO 18312-1:2012 - Mechanical vibration and shock - Measurement of vibration power flow from machines into connected support structures - Part 1: Direct method defines a standardized direct measurement procedure to quantify the vibration power a machine transmits into its supporting structure through bolted joints. The method evaluates vibration power in the six degrees of freedom (three translations and three rotations) using measurements of force and velocity (or acceleration) at joints and processing their cross‑spectra in the frequency domain. The procedure assumes stationary random vibration and adequately rigid supports (not applicable to resilient foundations that exhibit resonance in the frequency range of interest).

Key Topics

• Scope and assumptions
  • Measurement of vibration power flow from machines or pipelines into directly bolted support structures.
  • Assumes stationary random vibration and rigid foundations.
• Degrees of freedom
  • Evaluation of components in 6 degrees of freedom (3 linear, 3 rotational); rotational components may be omitted if measurement is impractical.
• Transducers and mounting
  • Use of multi‑axial vibration transducers (or uni‑axial accelerometers) and integrated triaxial force transducers mounted at bolted joints.
  • Mounting practices referenced to ISO 5348.
• Force measurement methods
  • Single‑transducer insertion (requires stiffness correction) or two‑transducer differential method to obtain net transmitted force.
  • Importance of maintaining bolt torque when inserting transducers.
• Signal processing
  • Compute cross‑spectrum of force and velocity pairs over narrow frequency bands (example: Δf = 1 Hz) to obtain vibration power spectra.
  • Use of FFT analyzers, multi‑channel analysers, and phase correction between channels.
• Frequency limits and uncertainty
  • Practical upper/lower frequency limits and measurement uncertainty considerations are specified (see standard for detailed metrological requirements).
• Reporting
  • Data presentation and test report requirements, including band sums (octave or one‑third‑octave) and total emitted vibration power.

Applications

ISO 18312-1 is practical for:

• Specifying vibration power emission of rotating machinery, compressors, pumps, and pipelines at bolted joints.
• Identifying severity and dominant paths of vibration power for diagnostics.
• Planning and validating vibration control measures (isolation, balancing, structural reinforcement).
• Engineers and practitioners in vibration testing, condition monitoring, mechanical design, and noise & vibration mitigation.

Related Standards

• ISO 18312-2 - Indirect method (companion part)
• ISO 2041 - Vocabulary for mechanical vibration and shock (normative reference)
• ISO 5348 - Accelerometer mounting (normative reference)

Keywords: ISO 18312-1, vibration power flow, mechanical vibration and shock, vibration measurement, bolted joints, force transducer, velocity transducer, direct method, vibration power spectrum, machine vibration, vibration control.