# BS ISO 2041:2018 pdf free

**BS ISO 2041**:2018 pdf free.Mechanical vibration, shock and condition monitoring – Vocabulary

number of modes with respect to a given bandwidth

Note 1 to entry: Modal density is a measure widely used in structural dynamics as a diagnostic tool in assessing vibration power flow in complex, structural systems. It can play a crucial role in determining changes in vibration power flow that may be a precursor to fatigue failure in some part of the structure, or a metric used in structural condition monitoring evaluations. In addition to these applications, it is a parameter required by the Statistical Energy Analysis method for evaluating the high-frequency response of complex structures and in selecting appropriate vibration-control methods and devices.

complex ratio of force to velocity at a specified point and degree-of-freedom in a mechanical system

Note 1 to entry: The force and velocity may be taken at the same or different points and degrees-of-freedom in the system undergoing simple harmonic motion.

Note 2 to entry: In the case of torsional mechanical impedance, the terms “force” and “velocity” should be replaced by “torque” and “angular velocity”, respectively.

Note 3 to entry: In general, the term “impedance” applies to linear systems only.

Note 4 to entry: The concept is extended to nonlinear systems where the term “incremental impedance” is used to describe a similar quantity.

ratio of the applied excitation complex force to the resulting complex velocity with all other connection points of the system free, i.e. having zero restraining forces

Note 1 to entry: Historically, often no distinction has been made between blocked impedance and free impedance.Caution should, therefore, be exercised in interpreting published data.

Note 2 to entry: Free impedance is the arithmetic reciprocal of a single element of the mobility matrix. While experimentally determined free impedances could be assembled into a matrix, this matrix would be quite different from the blocked impedance matrix resulting from mathematical modelling of the structure and,therefore, would not conform to the requirements for using mechanical impedance in an overall theoretical analysis of the system.BS ISO 2041 pdf free download.