MEEG 655/855: Principles of Composites Manufacturing
Due Date: Lecture6(Sept. 13th)
I: Please select a composite manufacturing process to fabricate the following components. Choose the materials, i.e fibers (will it be glass, kevlar or carbon, will it be chopped fibers, continuous strands or woven) and resin (thermoset or thermoplastic). State your reasons for selection of the process and the materials. .
1. Turbine Housing for Jet Engines
2.Fuselage for Boeing Dreamliner
3.High Pressure tanks for Hydrogen Storage under 10, 000 Psi
4. Carbon Composite Car Chassis
5.Rocket Motor Casing
II. Composite materials are replacing traditional materials in many
applications. List at least 5 examples of polymer composite material being
used in different applications since 2000. Also state the reasons for the
replacement. Can you think of a component or an application that is currently
not being made of composite materials but will benefit greatly if it was
? State the benefits
III. Consider a converging pultrusion die as shown below.
As you pull the fibers through it does the resin pressure increase or decrease
along the axial direction inside the die ? State you reason. Is it advisable
to pull in the direction of converging or would it be more useful to pull
in the opposite direction ?
IV. Consider unidirectional stretching of a cylinder as shown in the figure below. At any time, t, assume that R(t) is independent of z.
(a) Using only the conservation of mass show that the velocity field
is given by
uz = U *z/L(t)
and ur = - U *r/2*L(t)
b) find the components of the strain rate tensor
c) Neglecting surface tension and inertia, calculate the force F required
to pull the Newtonian Viscous cylinder.
MEEG 655/855: Principles of Composites Manufacturing
Due Date: Sept. 27th
I Squeeze flow between two circular disks:
Consider a thermoplastic containing fibers (GMT) material being squeezed between two circular platens. The radius of the disks is R and is much larger that the initial thickness hi. The material GMT is highly viscous and may be assumed to behave like a Newtonian fluid. If you continue to move the two disks towards each other at the speed of
, how will the force required change with the thickness, radius of the disks and the material properties of GMT? Assume that the material sticks on the platen walls and does not slip along them. Will the force, F required also depend on the initial thickness hi of the material? Justify your answer
II: Circulating slow flow of a viscous resin
A thin plate (thickness 2kH) moves with constant velocity V through a wide and long container (thickness 2H, where H<< length (L) and the width (W)) filled with an incompressible viscous liquid. The fluid circulates in the container, moving to the right along the central core and moving to the left close to the fixed wall of the container.
a. It is desired to find the velocity distribution in the container, away from the end disturbances. k is just slightly less than unity.
b. Also calculate the force, required to move the plate if we ignore the end disturbances in terms of the V, L,W,k,H and viscosity, h of the viscous fluid.
c. If you modify this set-up such that the plate was a circular fiber tow and the container was cylindrical, would any fluid impregate inside the fiber tow?
Do you expect the most impregnation downstream or upstream ? Why ?
III Permeability Measurement Experiment
The goal is to find the permeability of a glass fabric and the possible variation in such a measurement. The permeability characterization experiment will be performed for a selected fiber volume fraction with the fluid being injected under constant injection pressure. A video camera will record the visible flow front progression through the transparent mold lid. A scale may be placed along the mold length to later extract the information of location of the flow front as a function of time.
Steps in the procedure that should be followed are as follows:
1. Partially assemble the mold
2. Carefully cut the fabric layers (sufficient for two experiments)
3. Stack the fabric layer in the mold cavity
4. Close the mold
5. Prepare the corn syrup and water mixture and measure its viscosity (should be in the range of 50 to 500 cp) ( one cp is the viscosity of water)
6. Place the fluid in the container and pressurize it.
7. Inject the fluid into the mold with constant pressure at the inlet
8. Record the motion of the flow front with the camera
9. Stop the experiment when the fluid reaches the vent
10. Dismantle the setup
11. Clean up the mold and the area
12. Process the data to find the permeabilityMATERIAL AND PROCESS INFORMATION
Reinforcement material: Fiberglass: Random Mat
Density: 2570 kg/m3
Aerial weight: to be measured
Number of layers: 2 (for each experiment)
Mold: Cavity thickness: 3.2 mm and Width: 206.4 mm
Resin system: Mixture of corn syrup and water
Viscosity: to be measured
Injection pressure to be obtained during the experiment: 10-15 psi (Please DO NOT exceed)
OTHER INFORMATION
A. Measure the aerial weight of the preform used and deduce its porosity value for the experiment using the dimensions of the mold
B. Conduct the experiment in a group of 3 or 4 and save the data collection video of the experiment (bring a memory stick or a zip disk)
C. Find the permeability of the preform for the fiber volume fraction you used for your experiment. Show all your calculations on how you obtained the permeability value.
D. List possible errors in your experiments and recommend how you would improve the experiment.The group can share the experimental data but the report should be written individually.
Justin Alms (jbalms@udel.edu) will help you with the experiment. Groups will be assigned in class.
Please see Justin in room 007 and he will walk you over to CCM where you will be given the materials and
instruction for conducting the experiment.