ISO 18312-2:2012

Overview

ISO 18312-2:2012 - Mechanical vibration and shock - Measurement of vibration power flow from machines into connected support structures - Part 2: Indirect method specifies an indirect measurement method for quantifying the vibration power a machine (or pipeline) transmits into supporting structures through vibration isolators. The method characterizes emitted vibration power in six degrees of freedom (three translations and three rotations) using signals from two sets of velocity or acceleration transducers: one on the machine side (input) and one on the foundation side (output). The standard assumes the machine vibration can be treated as a stationary random process and defines how to compute vibration power spectra from cross-spectral data and isolator dynamic stiffness.

Key topics and technical requirements

• Measurement principle: Use of paired velocity (or acceleration) transducers at isolator connection points to capture input and output motion.
• Spectral processing: Computation of vibration power components from the velocity cross-spectrum in narrow-band or one-third-octave bands.
• Dynamic stiffness: Inclusion of input, output and transfer dynamic stiffness matrices of isolators in calculations; methods for obtaining these (laboratory measurement per ISO 10846-1 or numerical estimation).
• Six degrees of freedom: Evaluation of translational and rotational power components at each mount.
• Test procedures and instrumentation: Guidance on transducer placement, number of isolators to measure, typical signal processing, metrological specifications and measurement uncertainty.
• Data reporting: Requirements for presenting vibration power spectra, levels (dB re 1 pW), and test reports.
• Annexes: Informative annexes on constructing dynamic stiffness matrices and simple isolator geometries to illustrate matrix components.
• Limits and applicability: Upper frequency limits for the indirect method are defined in the standard; applicable when vibration is stationary random process.

Applications and users

ISO 18312-2 is used to:

• Evaluate isolator design and machinery-support interactions during design and acceptance testing.
• Provide objective data for technical specifications and allowable machine vibration power emission.
• Select cost-effective vibration control or isolation strategies.
• Support vibration diagnostics and fault investigation.

Typical users:

• Vibration and acoustic consultants, test laboratories, OEMs, rotating-equipment and pump manufacturers, civil/structural engineers, and condition‑monitoring teams.

Related standards

• ISO 18312-1 (Part 1: Direct method)
• ISO 10846-1 (vibro-acoustic transfer properties of resilient elements)
• ISO 2041 (vibration vocabulary)
• ISO 5348 (accelerometer mounting)

Keywords: ISO 18312-2:2012, vibration power, indirect method, vibration isolators, dynamic stiffness, velocity cross-spectrum, accelerometers, mechanical vibration and shock.