Title: Measuring Fracture Energy of Fire Resistant Materials
1Building and Fire Research Laboratory, NIST
Measuring Fracture Energy of Fire Resistant
Materials
2Experimental Set-up
3Experimental Procedure
4 STEPS
- Step 1 Record load (P), displacement (u) and
the corresponding crack length (a) throughout a
test. - Step 2 Calculate compliance, C u/P.
- Step 3 Plot log C versus log a to get n
(which the slope of the plot). - Step 4 Calculate GC.
4Experimental Procedure
4 STEPS
- Step 1 Record load (P), displacement (u) and
the corresponding crack length (a) throughout a
test. - Step 2 Calculate compliance, C u/P.
- Step 3 Plot log C versus log a to get n
(which the slope of the plot). - Step 4 Calculate GC.
5STEP 1 Measure P, u and a
u, P
Measurement from a testing machine
u
P
6STEP 1 Measure P, u and a
u, P
Simple Ratio calculation
Length in the picture
Actual crack length
Measurement from a camera or microscope and using
the equation.
Measured total length of the substrate, not in
picture
Length in the picture
7STEP 1 Measure P, u and a
Illustration 1 FRM C
8STEP 1 Measure P, u and a
a
9STEP 1 Measure P, u and a
a
10STEP 1 Measure P, u and a
a
11STEP 1 Measure P, u and a
a
12STEP 1 Measure P, u and a
a
13STEP 1 Measure P, u and a
a
14STEP 1 Measure P, u and a
a
15STEP 1 Measure P, u and a
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16STEP 1 Measure P, u and a
a
17STEP 1 Measure P, u and a
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18STEP 1 Measure P, u and a
a
19STEP 1 Measure P, u and a
a
20STEP 1 Measure P, u and a
a
21STEP 1 Measure P, u and a
a
22STEP 1 Measure P, u and a
a
23STEP 1 Measure P, u and a
Illustration 2 FRM G
24STEP 1 Measure P, u and a
a
25STEP 1 Measure P, u and a
a
26STEP 1 Measure P, u and a
a
27STEP 1 Measure P, u and a
a
28STEP 1 Measure P, u and a
a
29STEP 1 Measure P, u and a
a
30STEP 1 Measure P, u and a
a
31STEP 1 Measure P, u and a
a
32STEP 1 Measure P, u and a
a
33STEP 1 Measure P, u and a
a
34STEP 1 Measure P, u and a
a
35STEP 1 Measure P, u and a
a
36STEP 1 Measure P, u and a
a
37STEP 1 Measure P, u and a
a
38STEP 1 Measure P, u and a
a
39Experimental Procedure
4 STEPS
- Step 1 Record load (P), displacement (u) and
the corresponding crack length (a) throughout a
test. - Step 2 Calculate compliance, C u/P.
- Step 3 Plot log C versus log a to get n
(which the slope of the plot). - Step 4 Calculate GC.
40STEP 2 Calculate compliance
Calculate the compliance, C
Displacement
Load
41Experimental Procedure
4 STEPS
- Step 1 Record load (P), displacement (u) and
the corresponding crack length (a) throughout a
test. - Step 2 Calculate compliance, C u/P.
- Step 3 Plot log C versus log a to get n
(which the slope of the plot). - Step 4 Calculate GC.
42STEP 3 Find n
- Plot log C versus log a
- Fit the data with a linear regression.
n the slope of the line 2.6727
43Experimental Procedure
4 STEPS
- Step 1 Record load (P), displacement (u) and
the corresponding crack length (a) throughout a
test. - Step 2 Calculate compliance, C u/P.
- Step 3 Plot log C versus log a to get n
(which the slope of the plot). - Step 4 Calculate GC.
44STEP 4 Calculate Gc
Calculate GC
Slope of a plot of log C (u/P) versus log
a (example 2.67)
Load (P)
Displacement (u)
Substrate width, (measured in lab)
Crack length a
45STEP 4 Calculate Gc
Statistical Analysis
Average Gc 5.84 J/m2 Standard deviation 0.59
J/m2