The strength demand of carbon fiber composite material
Be introduced when generation carbon fiber when plane airframe structure, its characteristic is to compare flexibility high to the model is measured and compare intensity high, and rupture percentage elongation is relatively inferior (it is about 1% ) . Compare with the phase of traditional metal stuff such as aluminium and titanium, carbon fiber composite material has a lot of advantages. The main good point that uses composite material in aerospace application was to reduce weight. For example, replace aluminium alloy through enhancing composite material with carbon fiber, weight can decrease 12% .
This kind of weight is economic can be used at reducing specific fuel consumption or raise effective load, maneuverability and rate. Other dominant position includes composite material to be able to bear or endure exceedingly goodly fatigue, corrosion resistance reachs his to decrease brace up function. Meanwhile, the intensity of carbon fiber increases (graph 1) come true through the following means: (1) rise not carbonization fibrous purity reduces its blemish; (2) the taller tension in improvement production public errand and fiber production process.
▲ pursues the main function of 1 common carbon fiber
The defect of inchoate epoxy resin is to have opposite taller hygroscopic (graph 2) and the sensitivity that issues pair of temperature in moisture existence (graph 3) , bring about matrix premature bate (drop vitrification transition temperature) . To damp condition (70 ℃ / 85%RH, graph 2) , t300/914 adds more weight inside shorter time. Nevertheless, two kinds of composite material show Fickian to diffuse behavior, as the addition that reveals time, quality increases, till composite material by water saturation.
▲ pursues 3 generation and the moisture absorption function of the 2nd acting epoxy resin
Generally speaking, water branch increases colophony / the flexibility of adhesive and extend a gender, reduce stretch model quantity and intensity. Accordingly, cannot not gift high pressure of carbon fiber composite material shrinks intensity. However, in certain polymer, can observe active water divides effect. In fact, if bibulous when the loss of material of small element quantity in polymer changes effect than water model (drop vitrification transition temperature) more remarkable, criterion the stretch model quantity when moisture ageing can increase.
Composite material is in solidify process besides producing thermal stress, still produced the change of leftover stress. To cutting Chu Nengmo to measure, also be the function of moisture content. Cut modular quantity to begin to drop between 90-120 ℃ (graph 3) .
▲ pursues the function of damp and hot of composite material of 3 different types
Part 3:CFC (Carbon Fiber Composites) production requirement and craft
To improve CFC performance, must develop new workmanship. Should optimize spare parts and the dependability that assemble the cost with assuring lowest and structure. In aviation industry, reduce specific fuel consumption and environmental influence to having very high demand.
Decrease must come true with the way with a kind of efficient economy again, and this can pass stylist and the many channel a universal genius between production engineer to be able to come true only. Nevertheless, the amount of detail spare parts and fastener also must decrease considerably.
The function of composite material spare parts depends on not only compositive material, still depend on the process that its conformity assembles with undertaking for final part. These production technologies depend on its chemistry function, main component is 3 kinds: (1) semi-manufactured goods is made; (2) open shape (shop silk, spray, fiber is twined, pull crowded, automatic fiber to place, solidify) ; (3) close shape (note model to shape, colophony move shapes, vacuum is auxiliary colophony infuse, compress shape) . In production process, must avoid space and systole. Air hole and hole rate are one of the most crucial questions in production process
Somebody puts forward, the main structure such as wing, airframe must resist exhaustion and environmental influence. These two character increased to make the cost of the process. On the other hand, cheaper material and faster workmanship can be used in 2 level structure.
Must pass control to satisfy strict stiffness and intensity requirement relatively at devising the fiber way of load like the component such as wing. Carbon fiber beforehand because its performance is superior,dip expects, apply in aviation industry most. Carbon fiber beforehand dip makings basically has two kinds of producer type: One kind is heat colophony directly, in order to reduce its viscosity, facilitate distribute equably between fiber, call hot frit way. Another kind reduces viscosity to come to colophony dissolve in solvent, after waiting for colophony to contain dip fiber, heat again make solvent volatilizes, call solution dipping process.
At present carbon fiber beforehand the hot frit law with dip commonly used makings can be divided again for one footwork (graph 4) with two footwork (graph 5) . In two footwork the first pace needs first preparation colophony film, undertake next beforehand dip processing, at present domestic carbon fiber beforehand dip expects about 90% craft use hot frit two footwork.
▲ pursues 4 carbon fiber beforehand dip makings heats up frit one footwork shapes craft
▲ pursues 5 carbon fiber beforehand dip makings heats up frit two footwork shape craft