GB/T 40072-2021Strength test method for submersible metallic framework (English PDF)

3.1 Submersible

The general term for various underwater operating appliances. [GB/T 13407-1992, definition 2.1.1]

3.2 Submersible metallic framework

A spatial three-dimensional carrier frame made of metal materials for integrating various equipment and systems belonging to the submersible.

3.3 Trim angle of framework

Under the action of external force, the angle between the cross section of the frame and the vertical plane.

3.4 Heeling angle of framework

Under the action of external force, the angle between the vertical section of the frame and the vertical plane.

4.1 Test environmental conditions

The temperature of the test site environment. 20°C±5°C; Relative humidity. 50%~70%.

4.2 Test equipment

The instruments and meters used in the test have passed the metrological verification and are within the validity period of the metrological verification. The test instruments and accuracy are as follows.

a) Resistance strain gauge. During the test, the deformation of the metal frame of the submersible causes the change in the resistance of the strain gauge in the measured area.

The sensitivity coefficient should be 2%~3%, and the dispersion should be ±2%.

b) Digital strain gauge. Convert the strain measurement signal into strain data, the accuracy should be ±0.05%.

c) Laser tracker. used to measure the overall displacement of the metal frame structure of the submersible, with an accuracy of ±21µm/m.

d) Loading cylinder. The loading cylinder used to simulate the load borne by the frame of the submersible shall have a proportional linkage loading capacity.

The loading capacity should not be less than 1.5 times the maximum loading force of the test, and the accuracy should be ±20kg.

4.3 Non-destructive testing

The welded joints of the frame shall be subjected to non-destructive testing of welds. Non-destructive testing includes weld surface penetration testing (or magnetic particle testing) 100% welds The length of the weld is not less than 25% of the weld length by ultrasonic inspection and X-ray inspection. For lifting parts, battery compartment parts, etc., the weight is relatively The internal inspection of the frame joint welds of large equipment and load-bearing parts should be carried out by ultrasonic or X-ray. The number and specific requirements of the random inspection The request is negotiated and determined by both interested parties.

4.4 Auxiliary test of loading system

Before the test, the loading system should be tested in advance. The test can be carried out with an I-beam instead of the frame to adjust each oil The loading speed of the cylinders until each cylinder can be loaded proportionally and simultaneously during all the loading processes.

In the test, each loading cylinder should be in the same loading ratio during each step of the loading process (the load applied by a single cylinder is the same as that of the cylinder.

Larger test load ratio) load in the same time. Therefore, each oil cylinder should have automatic speed regulation function, and the whole system should have linkage loading Features.

4.5 Auxiliary test of tooling mast

The metal frame of the submersible is suspended on the portal suspension frame according to the designed lifting method. Before the frame test, the door-shaped hanging frame should be directly The frame is loaded, and its displacement under each test load is measured.

This auxiliary test only needs to measure the displacement under 2.0 times the weight of the submersible. The displacement of the mast under other loading steps can be folded in the same proportion Calculated, if the displacement of the portal hanging frame is 4mm under 2.0 times the weight of the submersible, then at 1.0 times the weight of the submersible, the portal hanging frame The equivalent displacement of the equivalent ratio is 2mm.

5.1 Maximum total bending load

The simulated load should accurately simulate the position generated by the maximum total bending load of the metal frame of the submersible, and the longitudinal coordinate error should not be greater than the frame. 2% of the total length of the rack.

5.2 Lifting force

The tensile force generated by the simulated load at the lifting point is equal to the actual lifting force of the submersible, and the maximum does not exceed the actual lifting force of the submersible 1.05 times.

5.3 Simulating local critical loads

Ability to simulate local critical loads. For equipment whose weight exceeds 10% or more of the total weight of the submersible, the simulated load shall be arranged separately.

Equipment weighing less than 10% of the total weight of the submersible can be combined and loaded.

5.4 Total vertical load, total bending load

The deviation of the total vertical simulation load from the design value should be controlled within 5%, and the deviation of the total bending simulation load from the design value should be controlled Within 10%.

6.1 Strain measurement

6.1.1 The distribution area of resistance strain gauges mainly has the following two parts.

a) According to the local maximum stress area obtained by the calculation result, measure its maximum stress state;

b) In accordance with the measurement position specified in 5.3.1.1 of CB1255-1995, in the typical structural area of the submersible frame, such as the top longitudinal stringer, Measure the average stress level of the side longitudinal girders, the midship area of the bottom longitudinal girders, the middle of the diagonal braces, the lifting lugs, etc.

6.1.2 The beam is measured with a one-way strain gauge. The typical patch method is shown in Figure 1. The connection node between the beam and the beam and the connection on the frame The plate uses three-way strain gauges.

6.2 Deformation measurement

6.2.1 Before the test, adjust the frame to a horizontal state, install a laser light source near its lifting point, and illuminate the horizontal light emitted by the light source.

To the white paper marked with graduations arranged vertically outside the frame.

6.2.2 According to the vertical distance between the white paper and the light source and the vertical movement distance of the light falling on the white paper in the test, the frame trim angle in the test theta is calculated according to formula (1), and the calculation result retains 3 significant digits, as shown in Figure 2. Where. theta---The trim angle of the metal frame, in degrees (°);

L---The horizontal distance between the white paper and the light source point of the laser tracker, in meters (m); d---The vertical movement distance of the laser projection point on the white paper, in meters (m).

7.1 Preload test with 0.5 times working load

The test steps are as follows.

a) The preload test is carried out in the order of 0 times, 0.1 times, 0.3 times, 0.5 times, 0.3 times, 0.1 times, and 0 times working load.

b) The preload test must complete the following tests.

1) After all loading points are loaded synchronously and proportionally, the frame should be basically horizontal, and the maximum frame vertical inclination angle should be within 5°.

2) The maximum frame angle of heel should be within 3°. If this requirement cannot be met, fine-tune the loading position of the loading cylinder should be Measures such as high loading accuracy to improve the tilt angle.

3) Check the synchronization of the loading of each loading cylinder, collect strain data and frame deformation data, and confirm the reliability of the measurement data.

7.2 Formal loading test with 2 times working load

The test steps are as follows.

a) The formal loading test should be loaded in stages, and the loading sequence should be 0 times, 0.5 times, 0.8 times, 1.0 times, 1.5 times, 1.8 times, and 2.0 times. The loads are carried out in sequence.

b) A holding time of not less than 0.5h should be carried out at 1.0 times working load and 2.0 times working load.

c) The unloading sequence follows the path opposite to the loading sequence. Unloading should slowly reduce the load.

d) Data collection of load value, strain value and deformation value should be carried out for each load step. At 1.0 times working load and 2.0 times working load Data should be collected before and after the retention of the load.

8.1 Non-destructive testing of welds

After the test, the welded seam of the metal frame undergoes 100% surface penetration test (or magnetic particle test) and meets the 8.2 quality score in NB/T 47013.5-2015 Class I regulations (or 9.2 quality grading regulations in NB/T 47013.4-2015) Class I qualified; ultrasonic inspection parts comply with NB/T 47013.3-2015 Qualified Class I in 5.3.9 board quality classification requirements; radiographic inspection parts comply with NB/T 47013.2-2015 in 6.3.4 quality classification 1 The general requirement is level II qualified.

8.2 Deformation

The space size after the test should be consistent with the data before the test.

8.3 Stress measurement

The maximum stress of the metal frame measured under a load of 2 times the weight of the equipment installed on the submersible shall be less than the allowable stress requirement. Allowable stress The value is sigma s/n, where sigma s is the yield strength of the material, n is the safety factor, and the safety factor is recommended not to be less than 3.