Carbon fiber composite pressure vessel reinforcing crack repair
Distinguished 'welding', fill board 'and other' traditional pipeline repair using patch 'method, using vacuum-assisted curing technology, without flare composite repair technology, will CFRP pasted directly be repaired area, beginning and ending drain reinforcing the role of carbon fiber and steel thermal expansion coefficient is very close, long service life. applies to steel containers and tank repair, be able to play the strength of the reinforcing structure, repair fatigue, buckling repair, can be used to repair partial surface, surface defects such as tanks, containers, etc. repair.
With the traditional mechanical repair method (riveted; welding; screwed) compared to carbon fiber composite vacuum repair technique has obvious advantages: (1) the composite strength, high specific modulus, structure repair after heavy glued small (2) the design of composite material, and can be designed ply material according to the requirement and force the situation. (3) The surface of the composite parts of complex shape using bonding curing technology for in situ repair. complex surfaces, composite patch repair than traditional mechanical repair easier to implement, but after the repair patch close bond with the parent, to maintain the original structure of the basic shape. (4) composite glued repair patch can increase the stiffness of damage zone, static strength reduce the crack tip stress intensity factor, glued patches do not need to subsidize the original structure opening, will not form a new source of stress concentration, help to improve the structure of damage tolerance and fatigue resistance. (5) The repair time is short, low cost. (6) repair equipment required is simple, there are repair kits, pumps and other equipment. (7) No flare, safe and reliable.
Carbon fiber composite patch repair technique
Composite patch repair glued on adhesive selection, materials and match components to be repaired, the surface treatment is to repair the structure and repair curing process and construction technology security, and other key technologies.
Adhesive is to achieve the intermediary role patch crack arrest, it is essential to choose the adhesive should be both good fatigue performance based on the actual level of bearing selection and use of environmental repair the structure, but also has a high shear, peel strength ., good chemical resistance and resistance to heat aging properties of the adhesive bonding of composite materials used in adhesive patches There are two major categories: one is a two-component adhesive, mainly used for room temperature curing repair of composite structures (a few two-component adhesive can be used for thermal bonding curing repair); the other is a film-like adhesive (film), for thermal bonding cured repair.
Composite patch with the repair of metal components match: composite patch should be at the lowest possible temperature curing, and consistent temperature curable and adhesives; patch coefficient of thermal expansion should match that of the parent material of foreign mostly boron / ring. Composite patch oxygen damage metal structure glued patch because boron / epoxy composites high cost, difficult process, so in the conventional industrial repair, the use of carbon / epoxy patch, relatively inexpensive carbon / epoxy composite materials in the aviation industry has long been widely used, suitable for the repair of complex structures.
Revamped structure surface treatment: Before glued finger, affect the structure of the binding force to remove surface oxide layer by mechanical means, to increase the mechanical joint surface contaminants; or structure of the surface in a controlled manner in a uniform layer of deposited oxide chemically Specialty or in plastic junction formation of chemical bonds, so that through the structure of the surface treatment has a high surface energy, so as to obtain a high bonding strength and durability. The most commonly used simple surface treatment method is to surface mechanical polishing coating a silane coupling agent. surface grinding machine requires at least reach St3 level.
Vacuum-assisted curing process: composite tank technology fixes curing process used is the 'vacuum-assisted curing process'.
Patch cured main controlling factor is the pressure, temperature and time. Due to the revamped site with the surrounding body structure composed of a complex thermal conductor, and structural forms, therefore, need a dedicated vacuum pump, supporting materials, and especially with tools to patch area offers continuous temperature and pressure protection.
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