1COMPOSITES DESIGN WORKSHOP II

MIC-MAC TOOL

Pranav Dhoj Shah, PhD

SESSION B: JANUARY 8, 2010

ABOUT STRENGTH RATIO R

STRENGTH RATIO R:

- Gives a measure of the strength of a laminate- Reciprocal of the failure index k- We have R/FPF and R/LPF (Ultimate)

FPFLPF (Ultimate)

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ABOUT STRENGTH RATIO R

HOW IS THE VALUE OF R REPORTED IN MIC-MAC?

First we will talk about the strength ratio, R, on the onset of first ply failure:R/FPF.

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A []50S Im6/epoxy [Eng] laminate is subjected to load as {N} = {1, 2, 0} k/in. [Example taken from book Strength and Life of Composites].

Find the optimum helical angle in terms of the strength. Use Mic-Mac in-plane with range from 0o-90o.

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TO DETERMINE THE STREGNTH OF A LAMINATE:

ABOUT STRENGTH RATIO R

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TO DETERMINE FAIL SAFE LOAD (SCALABLE WITH R):

a) In-plane loads

Application: Mic-Mac /InplaneMaterial: Im6/ep [SI]Laminate: [0/90]10sLoad applied: {N} = {1, 0, 0} MN/m

Observation: If we halve {N}, will strength ratio be twice of the original value?If we multiply {N} with the obtained R, what will happen?

ABOUT STRENGTH RATIO R

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TO DETERMINE FAIL SAFE LOAD (SCALABLE WITH R):

b) Bending loads

Exercise:

Application: Mic-Mac /FlexMaterial: Im6/ep [SI]Laminate: [0]50sMoment applied: {M} = {1, 0, 0} MN

Observation: If we halve {M}, will strength ratio be twice of the original value?If we multiply {M} with the obtained R, what will happen?

ABOUT STRENGTH RATIO R

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DOES FAILSAFE THICKNESS VARY LINEARLY WITH R?

a) In-plane loads (Yes)

ABOUT STRENGTH RATIO R

Application: Mic-Mac /InplaneMaterial: Im6/ep [SI]Laminate: [0/90]rsLoad applied: {N} = {1, 0, 0} MN/m

Observation: Change repeat r from 1 to 10 , thus increasing the thickness of the laminate.Plot effect of r on R/FPF using Chart-Quick.

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DOES FAILSAFE THICKNESS VARY LINEARLY WITH R?

a) Bending loads (No)

Exercise:

ABOUT STRENGTH RATIO R

Application: Mic-Mac /FlexMaterial: Im6/ep [SI]Laminate: [0/90]rsMoment applied: {M} = {1, 0, 0} MN

Observation: Change repeat r from 1 to 10 , thus increasing the thickness of the laminate.Plot effect of r on R/FPF using Chart-Quick.

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HAS HOMOGENIZATION ANY EFFECT ON THE VALUE OF R?

a) In-plane loads (No)

ABOUT STRENGTH RATIO R

Application: Mic-Mac /InplaneMaterial: T300/N5208 [Eng]Laminate: [010/r/9010/r] rsLoad applied: {N} = {1, 1, 0} kips/inch

Observation: Change repeat r from 1 to 10 , such that the laminate definition will be from [010/9010] s to [01/901] s . This way, the total thickness of the laminate will remain the same but the degree of homogenization will change. Plot the effect on R/FPF.

Non-homogenized Homogenized

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HAS HOMOGENIZATION ANY EFFECT ON THE VALUE OF R?

b) Bending loads (Yes)

Exercise:

ABOUT STRENGTH RATIO R

Application: Mic-Mac /FlexMaterial: T300/N5208 [Eng]Laminate: [010/r/9010/r]rsLoad applied: {M} = {1, 0, 0} kips

Observation: Change repeat r from 1 to 10 , such that the laminate definition will be from [010/9010] s to [01/901] s . This way, the total thickness of the laminate will remain the same but the degree of homogenization will change. Plot the effect on R/FPF.

What will happen if load definition is set as {M} = {1,1,0}.

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Note:

ABOUT STRENGTH RATIO R

Effectofvariousfactorssuchasthevaluesoftheflexuralstiffnessmatrix,flexuralstrainsf andthusstressf developedateachplywhicharedependentonthepositionoftheplyaffecttheresult.

Suchobservationsarenotalwaysobviousanditisagoodideatogetthehelpofcalculators,suchasMicMac,togettheresults.

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Generally, Mic-Mac applications use simultaneous degradation scheme.

FPF and LPF

OnonsetofFirstPlyFailure,allpliesaredegradedatonce(simultaneousdegradation)

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Material properties and strength degradation to obtain R/LPF

FPF and LPF

Refer to the book, Section 7 and 9 for further information.

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FPF and LPF

How is the degradation factor Em* determined?

Estimation using Mic-Mac.Observe the effect of Em* on R/LPF.

Take [0/90]s under {N}={1,0,0} and determine Em* for material Im6/ep [Eng]Change Em* from 0.01 to 1.

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FPF and LPF

EXERCISE

Plot FPF and LPF Strength ratios for [0/]s as changes from 0 to 90. The laminate is subjected to {N}={1,0,0} MN/m

Use:- Application: Mic-Mac/ Inplane- Material: Im6/epoxy [SI]- Laminate: [0/]s

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HOMEWORK 2.1 (Due on January 11, 2010)

Compare strength ratio in FPF for []s as changes from 0 to 90 for Im6/ep and E-glass/ep laminates. Both laminates are subjected to uniaxial tension, N ={1,0,0} MN/m

Use:- Application: Mic-Mac/ Duplex- Materials: Im6/epoxy [SI], E-Glass/epoxy [SI]- Laminate: []s

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HOMEWORK 2.2 (Due on January 11, 2010)

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Solve the homework problems from session 1 using MicMac.

Hint:For Problem 3, use MicMac/Inplane and note the signs of shear strains (cell F14).

For Problem 4, use MicMac/Duplex and set laminate 1 with ply as [0]s and laminate 2 with ply as [90]s. Define N= {1,0,0} for each laminate and compare the values of transverse strains for them (Cells E11 and E15).