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Q: Composite Material Mechanical Properties ( Answered 3 out of 5 stars,   1 Comment )
Question  
Subject: Composite Material Mechanical Properties
Category: Science
Asked by: jackknight-ga
List Price: $8.50
Posted: 04 Oct 2002 13:04 PDT
Expires: 03 Nov 2002 12:04 PST
Question ID: 72570
I am looking for some mechanical properties, preferably in English
units, of a composite called Hercules IM7/8551.  It is a graphite
(InterModulus) / epoxy prepreg.  More specifically I need the
following properties in both the longitudinal and transverse
directions for both tension and compression:

1. Ultimate Strength (Ultimate Stress)
2. Strain to Failure (Ultimate Strain)
3. Modulus of Elasticity (Young’s Modulus)
4. Poisson’s Ratio

Also needed are the flexure properties such as ultimate strength and
the flexure modulus.

Thank-You

Request for Question Clarification by livioflores-ga on 04 Oct 2002 14:36 PDT
I just found the following:

0 degree tensile strength 
0 degree tensile modulus 
0 degree tensile elongation  
90 degree tensile strength 
90 degree tensile modulus 
90 degree tensile elongation 
0 degree compression strength 
0 degree compression modulus 
0 degree short beam shear strength: 
cured ply thickness  
fiber volume 
Fiber/resin areal weight @ typical 35% resin content 

all in US units, 
is that the answer that you are looking for?

Clarification of Question by jackknight-ga on 07 Oct 2002 07:24 PDT
Yes, those properties that I am looking for.
Answer  
Subject: Re: Composite Material Mechanical Properties
Answered By: livioflores-ga on 08 Oct 2002 02:34 PDT
Rated:3 out of 5 stars
 
Hi jackknight!!

After your clarification, I will answer you this question in the
security that it is that you need. More than this, I think that I
found the properties that you listed first:
At the EWS, the Engineering workstation labs at the University of
Illinois, I found data related to an experiment where the composite
IM7/8551-7A is analyzed. There are two pages where this experiment is
commented and/or described.
First you can see this document: (to view this you must download the
file)
http://www.cen.uiuc.edu/~kittell/aae261/lab%206/lab6.doc


In this MS Word document you can find all the mechanical properties of
this composite.
The Abstract says:
"Abstract
	The mechanical properties of three IM7/8551-7A composite beams with
different fiber orientations were determined through a uniaxial
tension test.  Each beam was subjected to loading until failure
occurred, and basic material properties were determined from the
resulting stress-strain relations.  The material specimen that was
determined to have the strongest fiber orientation was the [0]8T
specimen, with fibers aligned along the longitudinal axis.  The
corresponding longitudinal modulus and failure loading were found to
be 124.96 GPa and 782 MPa, respectively."

The properties and their values found here are summed up:

The stress states of the materials were calculated by dividing the
applied load by the initial cross-sectional area.  Table 1 shows the
cured density of the specimens as well as the dimensions of the
specimens before and after loading.

Table 1: Density and Dimensions of Composite Specimens
	                     [0]8T    [454]2S  [90]16T
Cured density (kg/m3)	     1226	1586	  1766

Before Loading:
Thickness (mm)	             1.29	 2.80	    1.83
Width (mm)	            25.05	25.68	   25.41
Cross-section Area (mm2)    32.31	71.90	   46.50

After Loading:
Thickness (mm)	               - 	 2.23	    1.81
Width (mm)	               - 	25.59	   25.51
Cross-section Area (mm2)        -	57.07	   46.17


Experimentally determined material strength properties of the three
specimens are detailed in Table 2.

Table 2: Experimental Material Strength Properties
	                   [0]8T	[454]2S	[90]16T
Yield Stress (MPa)	    782.0	  54.4	          0.52
Ultimate Strength (MPa)	    782.0	  80.9	          1.16
Ultimate Strain (mm/mm)	     0.00628	   0.00921	  0.0216
Young's Modulus (GPa)	   124.96	   9.49	          0.12


Follows a complicated Matrix-based calculation to find the Poissons
Ratio.

Also included in Table 4 are the specific stiffness and strength of
the three composites.  These values are normalized to the cured
density of the composite beams.
Table 4: Theoretical and Experimental Composite Properties
	                           [0]8T	[454]2S	[90]16T
   Theoretical Values:
Longitudinal Modulus (Pa)	  1.659E+11	1.428E+11	9.269E+09
Transverse Modulus (Pa)	          9.269E+09	1.428E+11	1.659E+11
Shear Modulus (Pa)	          1.713E+11	4.279E+10	1.713E+11
Poisson's Ratio	                  1.395E-02	-5.831E-01	2.497E-01
    Experimental Values:
Longitudinal Modulus (MPa)	  1.250E+11	9.490E+09	1.200E+08
Percent Error (%)	            24.65	  93.35            98.71
    Normalized Values:
Specific Stiffness (m2/s2)	  1.019E+8	5.984E+6	         6.795E+4
Specific Strength (m2/s2)	  6.378E+5	5.101E+4 	  656.9


Appendix A: Theoretical Mechanical Properties of IM7/8551-7A Composite
Longitudinal Tensile Strength (GPa)	 1.95
Longitudinal Compressive Strength (GPa)	 1.72
Transverse Tensile Strength (MPa)	 33.0
Transverse Compressive Strength (MPa)    225
Shear Strength (MPa)	                 90.0
Shear Tensile Modulus (GPa)	        265
Matrix Tensile Modulus (GPa)	          3.60
Fiber Shear Modulus (GPa)	        106
Matrix Shear Modulus (GPa)	          1.44
Fiber Volume Fraction	                  0.62

Here is the end of this document. I strongly recommend you to download
and to read this document. You can download the file from here:
http://www.ews.uiuc.edu/~kittell/aae261/lab%206/


You can also see the following page in order to read more info related
to the experiment described above:
http://ssm7.aae.uiuc.edu/AAE262/labs/lab6/procedure.html


The EWS page is:
http://www.ews.uiuc.edu/


I have noticed that the composite used in this experiment is the
IM7/8551-7A, and I am not an expert in this subject, so may be there
are some difference between the composite IM7/8551-7A and the Hercules
IM7/8551 composite.
The IM7/8551-7A composite is described as follows:
"IM7/8551-7A composite is used in this experiment.  IM7 corresponds to
the fiber type, denoting a graphite fiber with intermediate modulus
(IM).  8551-7A is a special two-part epoxy resin system used in the
aerospace industry.
The composite comes in prepreg form, which is the term used when epoxy
is already pre-impregnated in the fiber system (Figure 1.6).  The
composite prepreg is slightly tacky to the touch at room temperature,
and must be stored at freezing temperatures (-70F) to prevent
crosslinking.  The composite is easy to cut at room temperature with a
sharp utility knife.  The epoxy will crosslink under the application
of heat from the hot press."
http://ssm7.aae.uiuc.edu/AAE262/labs/lab1/equipment.html


But I did not find any confirmation on if they are the same composite.

I found a site of a company called "Composite Tooling Corporation". In
its website there is a FAQs section and in the question 2 you can
read:

"Generally, carbon composites are two thirds the weight of aluminum,
and two and a half times as stiff.

Some data for a typical epoxy and intermediate-modulus fiber in a uni
directional composite (Hercules IM7/8551) @ 77 degrees F., in US
units, is as follows:

0 degree tensile strength      400,000 psi 
0 degree tensile modulus          24.5 x 10^6 psi 
0 degree tensile elongation        1.62 % 
90 degree tensile strength     11,100 psi 
90 degree tensile modulus       1.20 x 10^5 psi 
90 degree tensile elongation       0.92 % 
0 degree compression strength    240,000 psi 
0 degree compression modulus       21.5 x 10^5 psi 
0 degree short beam shear strength: 14,500 psi 
cured ply thickness                    0.0055 in. 
fiber volume                          62 % 
Fiber/resin areal weight @ typical 35% resin content    0.0443 lb/ft^2
"
http://www.graphite.com/FAQ.HTM


This is the data that I promised you. Making the conversions, there
are some difference in the values, comparing with the IM7/8551-7A
properties values.
This company sales composites and in its "For Sale" page they offer
from Hercules brand the composites IM7G/8551-7A and IM7G/X8551-7A.
http://www.graphite.com/FORSALE.HTM


May be you can contact this company and ask they about this. The
contact data is :
"Composite Tooling Corporation"
Corporate Offices
10909 Acoma SE
Albuquerque, New Mexico 87123-3343
Tel: (505) 294-8120 Fax: (505) 294-8012
E-mail: kee@graphite.com
http://www.graphite.com/MORE.HTM


Search strategy: 
Google Search using the following keywords

"Hercules IM7/8551"
Hercules IM7/8551 composite
im7 8551 composite

Most useful search result page: (the results page for the last keyword
listed):
://www.google.com/search?q=im7+8551+composite&hl=en&lr=&ie=UTF-8&start=0&sa=N


I hope this help you. If you need some clarification or have dificult
to open a link, please post a request of answer clarification, I will
respond to it.

Best Regards
livioflores-ga

Clarification of Answer by livioflores-ga on 08 Oct 2002 03:00 PDT
Hi!!
Please excuse about the tables, but when I copy to the field box where
I write my answers they appears well, but then...you can see the
result.
I will transcribe the most important values again, and for a complete
read, please refer to the document.

Reference:  [0]8T ; [454]2S ; [90]16T

Table 1: Density and Dimensions of Composite Specimens
Cured density (kg/m3)
 1226 ; 1586 ; 1766

Before Loading:
Thickness (mm)
1.29 ; 2.80 ; 1.83

Width (mm)
 25.05 ; 25.68 ; 25.41

Cross-section Area (mm2)
 32.31 ; 71.90 ; 46.50

After Loading:
Thickness (mm)
 - ; 2.23 ; 1.81
 
Width (mm)
 - ; 25.59 ; 25.51
 
Cross-section Area (mm2)
 - ; 57.07 ; 46.17

--------------------------------------------
Table 2: Experimental Material Strength Properties 
  [0]8T ; [454]2S ; [90]16T
 
Yield Stress (MPa)
 782.0 ; 54.4 ; 0.52
 
Ultimate Strength (MPa)
 782.0 ; 80.9 ; 1.16
 
Ultimate Strain (mm/mm)
 0.00628 ; 0.00921 ; 0.0216

Young's Modulus (GPa)
 124.96 ; 9.49 ; 0.12
 
----------------------------------
Table 4: Theoretical and Experimental Composite Properties 
  [0]8T ; [454]2S ; [90]16T
 
Theoretical Values:
 Longitudinal Modulus (Pa)
 1.659E+11 ; 1.428E+11 ; 9.269E+09
 
Transverse Modulus (Pa)
 9.269E+09 ; 1.428E+11 ; 1.659E+11
 
Shear Modulus (Pa)
 1.713E+11 ; 4.279E+10 ; 1.713E+11
 
Poisson's Ratio
 1.395E-02 ; -5.831E-01 ; 2.497E-01
 
Experimental Values:
 Longitudinal Modulus (MPa)
 1.250E+11 ; 9.490E+09 ; 1.200E+08
 
Percent Error (%)
 24.65 ; 93.35 ; 98.71
 
Normalized Values:
 Specific Stiffness (m2/s2)
 1.019E+8 ; 5.984E+6 ; 6.795E+4
 
Specific Strength (m2/s2)
 6.378E+5 ; 5.101E+4 ; 656.9
 
-------------------------------

I hope you can understand that.

Regards
livioflores-ga
jackknight-ga rated this answer:3 out of 5 stars

Comments  
Subject: Re: Composite Material Mechanical Properties
From: grimace-ga on 04 Oct 2002 13:28 PDT
 
Hi,

I can't find the data you need online - although others may have
better luck - but this publication would certainly have them:

International Encyclopedia of Composites
http://www.sampe.org/pubs/encyclopedia.html

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