Test method for accelerated hygrothermal aging of single side of winding shell

Abstract

The invention relates to a hygrothermal aging test technology, in particular to a test method for accelerated hygrothermal aging of a single face of a winding shell. Air in a shell cavity is heated before the shell is sealed, so that air pressure inside and outside the shell is balanced when a damp-heat aging test is carried out, the influence of internal pressure or external pressure load on the shell in the test is eliminated, and a sealing plug is ensured not to be ejected out. In the test process, the measure of regularly changing the laying direction is adopted to eliminate the material creep effect caused by the dead weight of the test piece. By adopting the test method, the key part of the metal joint of the scaled part can be prevented from rusting; aging of a metal joint and a wound composite material interface is prevented; an inner cavity of the winding shell is isolated from a humid and hot environment as far as possible; therefore, the single face of the winding shell structure is in an accelerated damp-heat aging environment which is close to the erosion condition of damp-heat conditions to winding shell materials in a natural storage state.

Description

Technical Field

[0001] The present invention relates to a wet heat aging test technology, and relates to a test method for accelerated wet heat aging of a single side of a wound shell. The accelerated wet heat aging test is carried out quickly and economically. The method is mainly used to carry out accelerated testing of a composite wound shell structure in a wet heat aging chamber to simulate the environmental effects of a structure or product represented by the shell structure being placed in a real storage environment for a long time. Background Art

[0002] The life evaluation of large-scale wound shell structures usually involves whether their performance will be affected by long-term storage in a storage environment. However, due to the long natural storage time, it is difficult to directly evaluate the naturally stored products. Therefore, the engineering usually adopts the method of accelerated aging in the laboratory to equivalently evaluate their storage life. Accelerated wet heat aging test is a widely used accelerated aging test technology. Common large-scale wound shell structures such as solid rocket engine shells are sealed in storage environments, so the humid atmosphere and oxygen in the environment penetrate from the outside to the inside. Existing storage evaluation methods mostly use material-level accelerated aging tests. The problem with this method is that the humid atmosphere penetrates inward from both sides of the material at the same time. Even for unsealed test pieces, due to the large number of pores on the cutting edges, water molecules will accelerate the penetration along the boundaries, resulting in the aging physical model of the material-level accelerated test being different from the actual storage conditions. Summary of the invention

[0003] The purpose of the present invention is to (1) prevent rust on key parts of metal joints of scaled parts; (2) prevent aging of the interface between metal joints and wrapped composite materials; (3) isolate the inner cavity of the wrapped shell from the humid and hot environment as much as possible; so that the wrapped shell structure is placed on one side in an accelerated humid and hot aging environment, close to the erosion of the wrapped shell material by humid and hot conditions under natural storage conditions. (4) Heat the air in the shell cavity before sealing the shell to ensure that the air pressure inside and outside the shell is balanced when conducting a humid and hot aging test, eliminate the influence of internal or external pressure loads on the shell during the test, and ensure that the sealing plug is not pushed out. (5) Take measures to regularly change the shelf direction during the test to eliminate the material creep effect caused by the deadweight of the test piece.

[0004] The technical solution of the present invention is a test method for accelerating the wet heat aging of a single-sided wound shell, and the specific implementation steps are as follows:

[0005] Step 1 Preparation before the test: a) Preparation before painting: Before painting, use a silk cloth dipped in acetone or gasoline to clean the surface dust on the metal surface to be protected; b) Prepare a conical flexible sealing plug for sealing; c) Spray anti-rust paint on the exposed metal joints. The end face of the metal joint is the key protection part, spray at least 5 times, and other parts except the end face should be sprayed at least 3 times; If the protection time of the anti-rust paint cannot meet the requirements of the wet heat aging test, after the anti-rust paint is sprayed, use a paint brush to brush high anti-corrosion solvent-free paint on all the sprayed surfaces for superimposed protection, and completely cover it; d) Apply putty: Apply waterproof putty at the junction of the metal head and the winding shell material;

[0006] Step 2: Air pressure balance and sealing: Place the treated winding shell at the same temperature as the aging test conditions and heat for 10 to 15 minutes; immediately use the conical flexible sealing plug 4 to slowly rotate and plug the metal joint hole when the heating is stopped. The above operation should be completed within 30 seconds. Then, apply a circle of waterproof putty to the junction line of the plug and the hole;

[0007] Step 3 Sealing inspection: After completing the above steps, place the sealed shell in a heating box, raise the temperature to the target test temperature of the damp heat aging test and keep it warm for at least 1 hour. During the insulation process, check through the visual window of the test box to see if the sealing plug is pushed out. If the sealing plug is pushed out, immediately cool the heating box and repeat step 2. If the sealing plug is not pushed out through the visual window of the test box after the insulation is completed, cool the sample and take it out to check again whether there is any crack in the sealing putty at the junction of the plug and the hole; if the sealing plug is pushed out and the sealing putty is cracked, repeat step 2;

[0008] Step 4: Humidity and heat aging test: place the treated shell test piece in a humidity and heat aging box to carry out the humidity and heat aging test. For long-term tests, the placement direction of the test piece should be rotated every 30 days to eliminate the material creep effect.

[0009] Furthermore, the conical flexible sealing plug is made of silicone rubber.

[0010] Furthermore, the taper of the conical flexible sealing plug is greater than 15°.

[0011] Furthermore, when the metal joint is sprayed with anti-rust paint, the spray head is 15 to 30 cm away from the metal surface.

[0012] Furthermore, when spraying anti-rust paint on metal joints, each coat should be allowed to dry before spraying, with at least 10 minutes between each coat.

[0013] Furthermore, when the protection duration of the anti-rust paint cannot reach the duration of the wet heat aging test, high anti-corrosion solvent-free paint can be selected for overlay coating to enhance the protection effect.

[0014] Furthermore, the key part is the exposed end face of the metal joint.

[0015] Furthermore, the other parts are the exposed parts of the metal joint that are in contact with the air except the end surface.

[0016] Furthermore, after the formal aging test begins, the test pieces should be rotated at least every 30 days.

[0017] Technical effect of the invention: The innovation of this method is that it takes into account the actual storage environment of the structure, seals the large shell simulation structure by preheating, protects the interior of the structure, and ensures the balance of air pressure inside and outside the shell, and the sealing plug will not be pushed out. For long-term tests, considering the self-weight of the structural material, the placement direction of the test piece is changed regularly to eliminate the creep effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the winding shell structure and protective parts of the present invention.

[0019] 1-wrap shell; 2-exposed metal head; 3-junction between metal head and wrap shell material; 4-conical flexible sealing plug. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings:

[0021] like Figure 1 As shown, a test method for accelerating the wet heat aging of a single-sided wound shell is described, and the specific implementation steps are as follows:

[0022] (1) Preparation before the test: (a) Preparation before painting: Before painting, use a silk cloth dipped in acetone or gasoline to clean the surface dust on the metal surface to be protected. (b) Prepare a conical flexible sealing plug for sealing; (c) Spray anti-rust paint on the exposed metal head 2. The end face of the metal joint is the key protection part, spray at least 5 times, and other parts except the end face are sprayed at least 3 times; the key part is the exposed end face of the metal joint.

[0023] Other parts are the exposed parts of the metal joint that are in contact with the air except the end face. When spraying the anti-rust paint on the metal joint, the nozzle should be 15 to 30 cm away from the metal surface. When spraying the anti-rust paint on the metal joint, wait for the previous coat to dry before each spraying, and leave at least 10 minutes between each coat. If the protection time of the anti-rust paint cannot meet the requirements of the wet heat aging test, after the anti-rust paint is sprayed, use a paint brush to brush high-corrosion solvent-free paint on all the sprayed surfaces for superimposed protection until it is completely covered; (d) Apply putty: Apply waterproof putty at the junction of the metal head and the wrapped shell material 3;

[0024] (2) Air pressure balance and sealing: Place the treated wound shell at the same temperature as the aging test conditions and heat for 10 to 15 minutes; when the heating is stopped, immediately use the conical flexible sealing plug 4 to slowly rotate and plug the metal joint hole. The above operation should be completed within 30 seconds. Then, use waterproof putty to apply a circle of the plug and the hole intersection line; the conical flexible sealing plug 4 is made of silicone rubber, and the taper of the conical flexible sealing plug is greater than 15°.

[0025] (3) Sealing inspection: After completing the above steps, place the sealed shell in a heating box, raise the temperature to the target test temperature of the damp heat aging test and keep it warm for at least 1 hour. During the insulation process, check through the visual window of the test box to see if the sealing plug is pushed out. If the sealing plug is pushed out, immediately cool the heating box and repeat step (2). If the sealing plug is not pushed out after the insulation is completed, cool the sample and take it out to check again whether there is any crack in the sealing putty at the junction of the plug and the hole. If the sealing plug is pushed out and the sealing putty has cracks, repeat step (2).

[0026] (4) Hygrothermal aging test: Place the treated shell test piece in a hygrothermal aging chamber for hygrothermal aging test. For long-term test, the test piece should be rotated every 30 days to eliminate the creep effect of the material. After the formal aging test begins, the test piece should be rotated at least every 30 days.

Claims

1. A test method for accelerated wet heat aging of a single-sided wound shell, characterized in that: The specific implementation steps are: Step 1 Preparation before the test: a) Preparation before painting: Before painting, use silk cloth dipped in acetone or gasoline to clean the surface dust on the metal surface to be protected; b) Prepare a conical flexible sealing plug for sealing; c) Spray anti-rust paint on the exposed metal head, the end face of the metal joint is the key protection part, spray at least 5 times, and other parts except the end face at least 3 times; If the protection time of the anti-rust paint cannot meet the requirements of the wet heat aging test, after the anti-rust paint is sprayed, use a paint brush to brush high anti-corrosion solvent-free paint on all the sprayed surfaces for superimposed protection, and completely cover it; d) Apply putty: Apply waterproof putty at the junction of the metal head and the winding shell material; Step 2: Air pressure balance and sealing: Place the treated winding shell at the same temperature as the aging test conditions and heat for 10 to 15 minutes; immediately use a conical flexible sealing plug to slowly rotate and plug the metal joint hole when the heating is stopped. The above operation should be completed within 30 seconds. Then, apply a circle of waterproof putty around the junction line of the plug and the hole; Step 3 Sealing inspection: After completing the above steps, place the sealed shell in a heating box, raise the temperature to the target test temperature of the damp heat aging test and keep it warm for at least 1 hour. During the insulation process, check through the visual window of the test box to see if the sealing plug is pushed out. If the sealing plug is pushed out, immediately cool the heating box and repeat step 2. If the sealing plug is not pushed out through the visual window of the test box after the insulation is completed, cool the sample and take it out to check again whether there is any crack in the sealing putty at the junction of the plug and the hole; if the sealing plug is pushed out and the sealing putty is cracked, repeat step 2; Step 4: Humidity and heat aging test: place the treated shell test piece in a humidity and heat aging box to carry out the humidity and heat aging test. For long-term tests, the placement direction of the test piece should be rotated every 30 days to eliminate the material creep effect.

2. The test method for accelerated damp heat aging of a single-sided wound shell according to claim 1, characterized in that: The conical flexible sealing plug is made of silicone rubber.

3. The test method for accelerated damp heat aging of a wound shell on one side according to claim 1, characterized in that: The taper of the conical flexible sealing plug is greater than 15°.

4. The test method for accelerated damp heat aging of a wound shell on one side according to claim 1, characterized in that: When the metal joint is sprayed with anti-rust paint, the spray head is 15 to 30 cm away from the metal surface.

5. The test method for accelerated damp heat aging of a single-sided wound shell according to claim 1, characterized in that: When spraying anti-rust paint on metal joints, wait for the previous coat to dry before spraying each coat, and leave at least 10 minutes between each coat.

6. The test method for accelerated damp heat aging of a wound shell on one side according to claim 1, characterized in that: When the protection duration of anti-rust paint cannot reach the duration of the wet heat aging test, you can choose to overlay high-corrosion anti-solvent-free paint to enhance the protection effect.

7. The test method for accelerated damp heat aging of a wound shell on one side according to claim 1, characterized in that: The key part is the exposed end face of the metal joint.

8. The test method for accelerated damp heat aging of a single-sided wound shell according to claim 1, characterized in that: The other parts are the exposed parts of the metal joint that come into contact with the air except the end faces.

9. The test method for accelerated damp heat aging of a wound shell on one side according to claim 1, characterized in that: After the formal aging test begins, the test pieces should be rotated at least every 30 days.

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