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SMC/BMC molding analysis

SMC/BMC molding analysis

Send:2018/11/28 6:37:44

  In China, moulding method accounts for only about 10% of all molding processes of composite materials. It is expected that the proportion of moulding method will increase to 25% by 2010, and the FRP output will reach 90-100 tons. The rapid development of molding method is mainly due to the rapid development of SMC and BMC/DMC in recent years.

  1, what is composite material? What is the relationship between composites and FRP?

  Composite materials are composed of two or more independent physical phases, including a bonding material (matrix) and a solid product of granular, fibrous or flaky materials. The simplest composite material is the "mud" with straw added to build the adobe house in the countryside. Soil is binder and straw is reinforced material. It can be seen that composite materials change all the time. It consists of two parts, one is matrix (system), the other is reinforced material.

  Composite materials can be classified into three categories according to their matrix materials.

  (1) polymer matrix composites;

  (2) metal matrix composites;

  (3) inorganic nonmetal matrix composites, such as ceramic matrix composites, inorganic glass fiber reinforced plastics, etc. Among them, polymer matrix composites account for more than 90% of all composites.

  Fiberglass reinforced plastics (FRP) belongs to polymer matrix composites. In polymer matrix composites, the amount of FRP accounts for more than 90% of the total.

  2, what is FRP? What are the characteristics of FRP?

  Fiberglass reinforced plastics (FRP) is neither glass nor steel, but the "common name" of FRP. It was first proposed by Lai Jifa, the former Minister of Building Materials in the late 1950s. It has been gradually recognized by the international industry, especially in the circle of Chinese people.

  FRP FRP is the abbreviation of Fiber Reinforced Plastics.

  FRP began in the 1940s, China began to engage in research and development in 1958, has been widely used in many areas of the national economy. FRP has many outstanding features:

  (1) Light weight and high strength, specific gravity between 1.5 and 2.0, only 1/4 to 1/5 of carbon steel, tensile strength is close, to exceed carbon steel, and strength (material strength divided by density) can be compared with high alloy steel. Therefore, it has obvious advantages in the application of high-pressure vessels such as aeronautics, rockets, spacecraft and other products which need to reduce their weight.

  (2) Chemical corrosion resistance: FRP is a good corrosion-resistant material. It has good resistance to acid, alkali, salt, various oils and organic solvents of general concentration. It has been widely applied to many fields of chemical anticorrosion and has achieved obvious economic benefits. It is replacing carbon steel, stainless steel, wood, nonferrous metals and so on.

  (3) Good electrical properties: FRP insulation (surface resistance, volume resistance, breakdown voltage, etc.) is high, and can be made into anti-static or conductive materials, in high frequency can maintain good dielectric properties, free from electromagnetic action, no reflection of electromagnetic waves, can pass through microwave.

  (4) Instantaneous Ultrahigh Temperature Resistance: Some FRP can withstand the instantaneous Ultrahigh Temperature above 3800 C and become the only choice of ablative materials such as rocket shell, nose cone and nozzle. It is for the purpose of "two bombs and one satellite" (atomic bomb, hydrogen bomb, artificial satellite) that China began to develop FRP. FRP has low thermal conductivity, 0.3-0.4 kcal/m.h.degree at room temperature, and only 1/100-1/1000 of metal. It is an excellent insulation material.

  (5) Notch-free sensitivity: There are a large number of independent fibers in fiber composites, with a few thousand fibers per square centimeter and tens of thousands of fibers per square centimeter. From a mechanical point of view, it is a typical statically indeterminate system and will not appear "notch sensitivity" like glass and metal (a rapid expansion of damage), even if the component is overloaded. A small amount of fiber breaks and the load is quickly redistributed on undamaged fibers. Therefore, FRP is suitable for making some components with high requirements, such as aircraft hub, helicopter rotor, tank wheel, helmet, etc.

  (6) Good fatigue resistance: Fatigue failure is a kind of low stress failure caused by the formation and propagation of microcracks under alternating load.

  (7) transparent and multi colored products can be produced.

  (8) Strong design adaptability, molding process characteristics more: FRP is a kind of material, but also a structure, through the selection of different materials and molding process to the greatest extent to meet the different requirements of different products.

  Every product is divided into two parts. FRP is not everything.

  (1) Low modulus of elasticity, FRP modulus of elasticity than wood twice, but 10 times smaller than steel, so in the product structure often feel inadequate rigidity, easy to deformation. It can be made into thin shell structure, sandwich structure, or by adding high modulus carbon fiber to improve the steel property of FRP.

  (2) Low long-term heat resistance, generally only in the long-term below 100? **, but through the use of high-performance resin, this temperature can be raised to 200-300 degrees Celsius.

  (3) there are aging phenomena: adding antioxidants, surface coating and so on.

  (4) wear resistance: wear resistant materials such as silicon carbide can be improved.

  Note: FRP products and semi-finished products of our company:

  1, SMC combined water tank; 2, SMC insulation board; 3, other SMC components (such as ammeter box, long horn, short horn, arc plate, power supply connector, insulation sleeve, etc.); 4, various phenolic, epoxy phenolic glass cloth insulation board; 5, various phenolic, epoxy phenolic glass cloth pipe, rod; 6, molding material, SMC material, BMC / DMC.


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