Strain, Force and distance

a particular grade of Nitinol SMA is capable of upto 6% strain recovery and develops an internal restoration stress of upto 300 MN m-2. Estimate the amount of force and distance of travel that could be triggered by warming a rod(20mm long,1mm diameter) of this material that had been permanently stretched(6%strain) when cold. Where do you start?

Calculating the second moment of area

It is necessary to design a square-section composite bar that will withstand an applied load without deflecting more than a specified amount.The design specification for the bar, including its dimensions and loading criteria, is given below. Using the formula below, calculate the second moment of area of the bar and use this to estimate the modulus of a composite material that will just meet the design specification. The composite is made up of polymer fibres all aligned along the length of the bar combined with an epoxy matrix and each has the properties listed below. Estimate the minimum volume fraction of fibres that the composite must contain to meet the design specification. Le... click for more

hoop stress

1. A pressure vessel is made of a cylindrical composite part produced by filament winding. Hoop winding is used in which the number of winding layer is 5 and the wall thickness for each layer is 1mm. The diameter of the vessel is 0.5m. The fiber material is known to be S-glass with a tensile strength of 4.5GPa, and the matrix material is polyester with a tensile strength of70MPa. The volume fraction of fiber is 60%. It is also known that the HOOP STRESS is the stress in a pipe wall acting circumferentially in a plane perpendicular to the longitudinal axis of the pipe and produced by the pressure of the fluid in the pipe. S=PD/2t S=hoop stress, in MPa P=internal pressure, in MPa D=out... click for more

internal pressure

2. The control of pulling force is of critical importance to pultrusion process. What are the major force components in different process stages? And how would they respond to the change of resin viscosity, pulling speed, temperature, coefficient of thermal expansion of composite mixture, degree of shrinking, and coefficient of friction between the composite and the die?

machining of composites

3. Machining of composites can be classified as conventional machining and non-traditional machining. Among each category, there are many processes. Describe each of those processes, by giving the brief definition of the process, listing the machine tools to remove materials, and discussing the pros and cons of the process.