Design stiffness increase

Static friction decreases with an increase in load, and the static coefficient of friction is lower than the dynamic coefficient. The tendency to creep must be considered carefliUy in FEP products designed for service under continuous stresses. Creep can be minimized by suitable fillers. Fillets are also used to improve wear resistance and stiffness. Compositions such as 30% bronze-fiUed FEP, 20% graphite-filled FEP, and 10% glass-fiber-filled FEP offer high PV values ( 400(kPa-m)/s) and are suitable for beatings. 

The obvious question is Ts there an optimum design for the corrugations Unfortunately the answer is No because if one wishes to increase transverse stiffness then the obvious thing to do is to increase D up to the point where buckling problems start to be a concern. Usually this is when D/h = 10, for short-term loading and less than this for long term loading because of the decrease in modulus of viscoelastic materials. 

There are different techniques that have been used for over a century to increase the modulus of elasticity of plastics. Orientation or the use of fillers and/or reinforcements such as RPs can modify the plastic. There is also the popular and extensively used approach of using geometrical design shapes that makes the best use of materials to improve stiffness even though it has a low modulus. Structural shapes that are applicable to all materials include shells, sandwich structures, and folded plate structures (Fig. 3-8). These widely used shapes employed include other shapes such as dimple sheet surfaces. They improve the flexural stiffness in one or more directions. 

A new flow channel design and extmder positioning were part of the high-tech development. The increased stiffness of this massive head and a vastly increased center section resulted in a total weight of 45,000 kg of the quadroplex head. 

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