GB/T 2423.101-2025Environmental testing - Part 2: Test methods - Test: Inclinations and swings (English PDF)

3.1 Inclination

The tilting or heeling of a ship from its normal horizontal reference plane.

Heeling and trimming refer to the angles at which a vessel tilts around its longitudinal (X-axis) and transverse (Y-axis) coordinate axes on a horizontal plane, respectively. The X-axis is the direction of the ship's travel, and the coordinate axes indicate directions as shown in Figure 1.

NOTE: There are two modes of inclination. Trimming and heeling.

3.2 Swing

It indicates the reciprocating angular movements of a ship deviating from its normal position and around one of its coordinate axes.

Roll, pitch, and yaw refer to the reciprocating angular displacement movements of a ship around its longitudinal (X-axis), transverse (Y-axis), and vertical (Z-axis) coordinate axes.

NOTE: There are three modes of swing. Roll, pitch, and yaw.

5.1 Sample condition

Whether the test sample is in working condition during the test shall be specified in the relevant standards.

5.2 Test stand

Inclination test may be conducted on a swing test stand or platform. Swing test, the combined inclination and swing test shall be conducted on a swing test stand. The requirements are as follows.

a) During inclination test, the test stand shall be able to stably maintain the specified position under its maximum test load, without significant swinging or drifting.

b) During swing test, the swing test stand shall be able to simulate at least one mode of ship swinging, typically roll and/or pitch. Its amplitude and period shall be continuously adjustable and meet the requirements of 5.5 and Clause 6.

c) When the swing test stand cannot meet the test mode required by the relevant standards, it is permissible to use a rotating installation direction, a different mode of test stand, or a method agreed upon by both parties for testing.

d) The swing waveform produced by the swing test stand after the test sample is installed shall be a continuous, smooth sine wave. The distortion of the angular displacement sine waveform shall be less than 15%.

5.3 Measurement requirements

During the test, the amplitude and period of inclination and swing shall be monitored.

5.4 Installation of sample

The test sample shall be installed according to the actual installation orientation and method in use, or as specified in relevant standards, in a form sufficient to withstand the specified test conditions, directly or using fixtures to install on the test platform. When multiple installation methods are available, the method that can withstand the most severe conditions shall be selected, or all installation methods shall be tested. The rigidity of the fixture shall be sufficient to ensure that the fixture does not deform significantly due to the weight of the test sample and the additional inertial force generated by swinging during the application of test conditions.

The additional mass and constraints imposed on the test sample by external connections necessary to ensure the operation or power supply of the test sample during the test shall be kept to a minimum or as similar as possible to those during actual installation.

In actual installation, equipment with shock absorbers shall be tested together with the shock absorbers.

5.5 Test control tolerances

The tolerances for inclination angle, swing angle (amplitude), and period are ±5% of the specified values.

6.1 Severity level of inclination test

The severity level of an inclination test is jointly determined by two parameters. the inclination angle and the test duration. It shall be selected from Table 1; special requirements may be specified according to relevant standards.

For an example of the application of test severity level, see B.2.

6.2 Severity level of swing test

The severity level of a sinusoidal swing test is jointly determined by three parameters. swing angle (pitch, roll, yaw), swing period, and test duration. It shall be selected from Table 2; special requirements may be specified according to relevant standards.

For an example of the application of test severity level, see B.2. […]