vibration.immission.coupling

Mounting the transducer, and what the meter may be wrong by (DIN 45669-2:2005-06).

DIN 45669-2 is the procedure the DIN 45669-1 meter is used with: where the transducers go, how they are coupled to the floor or the ground, how long a measurement runs and what keeps a disturbance out of it. Nearly all of that is judgement written down, and the little that is a number is here, because a number a measurement is planned by belongs where the plan is checked.

Loose mounting (5.3.2 and 5.3.3). A transducer set down without fastening walks or lifts off when the vibration is strong, and a coupling that is not force-locked resonates against the surface. The clause fixes both limits: a loose transducer measures without falsification up to 100 Hz vertically and 40 Hz horizontally, provided the peak acceleration in every direction stays at or below 3 m/s². On a hard surface it may stand on its own or on the device with rounded feet of Figure 1 b); on a soft covering it has to stand on the device with hardened steel spikes of Figure 1 a), about 2,5 kg together with the transducer, pressed and tapped through the covering. Above those limits the transducer is glued, screwed or plastered on, and on a sensitive hard surface such as tiles or parquet adhesive wax carries the horizontal component to 80 Hz.

Mass loading (7.2.4). The mass coupled to the object, transducer and device together, should be at most a hundredth of the mass the object vibrates with; a heavier transducer is a disturbance of kind $s_3$.

The instrument’s share of the error (8.1, Table 3). A meter that meets every single requirement of DIN 45669-1 may still be wrong on one displayed quantity, and Table 3 says by how much at a high confidence level: 15 % on an r.m.s.-based value and 20 % on a peak for class 1, 25 % and 35 % for class 2. The classes are the accuracy classes of the 1995 edition of Part 1; the 2010 edition dropped the distinction, so a meter of today is graded by the one set of tolerances and the table’s class 1 column is the one that applies to it.

What is not here. Measurement positions, directions, durations and the list of disturbances are text, and so is the coupling to the ground, where 5.3.4.1 warns that the coupling alone can move the reading by up to 15 dB.

Auto-generated from the source docstrings by scripts/generate_api_docs.py (make api-docs). Do not edit by hand.

check_loose_mounting(
    peak_acceleration_m_s2: float,
    upper_frequency_hz: float,
    *,
    direction: str,
    surface: str = 'hard',
) -> MountingCheck

May the transducer be set down without fastening? (5.3.2 and 5.3.3)

Loose mounting carries a vertical measurement to 100 Hz and a horizontal one to 40 Hz, provided the peak acceleration in every direction stays at or below 3 m/s². Above either limit the transducer is glued, screwed or plastered on. The limits are the same on a hard surface and on a soft covering; what differs is what the transducer stands on, which the result names.

Parameters

Returns: The verdict and the limits it was read against, as a MountingCheck.

Raises

Constant (float).

CLEARANCE_TO_DISTURBING_BODY_FACTOR = 1.5

Constant (float).

EMISSION_POINT_TRACK_DISTANCE_M = 8.0

Constant (float).

GROUND_COUPLING_DEVIATION_DB = 15.0

instrument_confidence_limit_percent(
    quantity: str,
    accuracy_class: int = 1,
) -> float

The confidence limit of the meter’s own error on one quantity (Table 3).

Parameters

Returns: The limit, in per cent of the displayed value.

Raises

Constant (mapping).

INSTRUMENT_CONFIDENCE_LIMITS_PERCENT = {'rms': (15.0, 25.0), 'peak': (20.0, 35.0)}

Constant (mapping).

LOOSE_MOUNTING_LIMITS_HZ = {'vertical': 100.0, 'horizontal': 40.0}

Constant (float).

LOOSE_MOUNTING_PEAK_ACCELERATION_M_S2 = 3.0

mass_loading_ratio(
    coupled_mass_kg: float,
    *,
    vibrating_mass_kg: float,
) -> float

The mass the transducer adds to the object, as a fraction (7.2.4).

The transducer and its coupling device together should add at most MASS_LOADING_RATIO_LIMIT of the mass the object vibrates with, which for a floor is the mass of the slab that moves at the highest frequency of the signal, not the mass of the building. Where that cannot be estimated, 7.2.4 says to add a second, uncoupled mass of the same order beside the transducer and see whether the reading moves.

Parameters

Returns: The ratio of the two, dimensionless; compare it with MASS_LOADING_RATIO_LIMIT.

Raises

Constant (float).

MASS_LOADING_RATIO_LIMIT = 0.01

MountingCheck(
    acceptable: bool,
    frequency_limit_hz: float,
    peak_acceleration_limit_m_s2: float,
    direction: str,
    surface: str,
    device: str,
)

Whether a transducer may be set down without fastening (5.3.2, 5.3.3).

Attributes

Constant (float).

SPIKED_DEVICE_MASS_KG = 2.5

Constant (float).

WAX_MOUNTING_HORIZONTAL_LIMIT_HZ = 80.0