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laboratory fibre composites
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Royal Institute of Technology (KTH)
Laboratory assignment SD2414 Fiber composites – Materials and Manufacturing
Teacher: Magnus Burman Students: Benjamin Krank, Simon Börjeson, Vivian van der Burgt Group number: 6 Date: 11 March 2011
This report describes the predictions of different laminate properties of a manufactured glass fiber – polyester composite. First the results are presented in the tables below and the manufacturing procedure is shown. This summarizes all the data of the laminate. In the second part the calculations of mechanical properties are given and explained. These predictions will be taken into consideration in the discussion part.
Part 1 Manufacturing of Laminates 1.1 Results
Layer Dimensions [cm] Weight [g] 1 38x40 103,52 38x40 108,53 38x40 105,54 38x40 105,9Total +/‐ 420
Reinforcement notation
Fiber type
Approximate areal weight [g/m2]
0° 45° ‐45° 90° Mat Total
C (Combi) E‐glass 350 ‐‐‐ ‐‐‐ 200 100 650
acking sequence # tS Stacking sequence Orientation 2 C/C/C/C [0/0/0/0]
Weight of resin 459,3 g.Weight of initiator 6,1 g.Weight of unused polyester 65 g.Weight of used polyester 394,3 g.
Resin type Unsaturated PolyesterPredicted resin weight 450,8 g
Room temperature 19°CPredicted gel time 45 minResin mixed (at what time) 13:09
Resin gels (at what time) 13:54Actual gel time 46 min
1.2 Calculations
l volume of the fibres and the matrix. First we calculated the tota E‐glass = 2600 kg/ m³ Polyester = 1200 kg/ m³ ρρ
The fibres have a fiber volume of appro mately 0.3. This means that 161 ml is 30% and the matrix volume is 70%. This will bring us to the xt calculation:
xi ne
T oly
, .
he total weight needed for the P ester is:
1.3 weight percent initiator has to the . to be add unsaturated polyester
0,013 450,8 5,9 .
P art 2 Prediction of Laminate Properties
2.1. Calculations 1. Consider the reinforcement only and cal late weight fraction of fibers. You need to calculate separate weight fraction forc nt type and fiber type.
cus for each rein eme
0.515
0.485
e ompo t n d laye have the weight fractions Th c si e is separated into the different orie te rs, which
0.538, 0.308 and 0.154 d These weight fractions account for the weight of the whole composite including fibers an
matrix in each fiber orientation respectively. Furthermore, the weight fractions on of irection is calculated in the following:
ly the fibers in each d
.· 0 277 · 0.158 · 0.0792
2. Then calculate the volume fractions o fferent reinforcement layers and the matrix e.g. using Equation 32 in Å
f the diström.
·· ·
0
1 0.671
.329
0.177, 0.101, 0 and 0.051 are calculated in the same way as .
sing “rule of mixtures”. Include cessary.
3. Estimate the moduli in the 0°, 90°, and 45° directions ue (be rs) where ne
es as follows: reinforcem nt efficiency factors tafacto
the tablThe efficiency factors were taken from° 1, ° 0, ° 0.1 and
The Young’s modulus is calculated s0.375
a · · ·
hus, the values for the different layers are . , . and . considering the material properties 70 and 3.85 . T
4. Estimate the moduli in the 9 45 the 10% rule”. 0°, 0°, and ° directions using “
· 5.59 · 2
·
The ‐factors in the different directions are ° 1, ° 0.1, ° 0.1, ° 0.1as well as 0.375. Thus, the ‐factors are 0 , 0.420 and 0.142. With these e
.627
·values, th Young’s moduli are calculated with
nd get . , . and . . a 5. Estimate strengths in the 0°, 90°, and 45° directions using “rule of mixtures”. Include
where necessary. Use an approximate failure strain of reinforcement efficiency factors2%.
aThe strengths are c lculated with ·
and amount to , and assuming a maximum strain of 0.02.
6. Estimate strengths in the 0°, 90 ng “the 10% rule”. °, and 45° ons usi
directi· 511.6
· . . .
2.2. Discussion Rule of Mixtures 10% ‐ rule Orientation E E 0° 1 6.31 325 16.03 3 20.590° 1 0.99 219 10.73 2 14.645° 5.86 116 3.64 72.8 T
able 1: results Emodulus and Strength.
The 10%‐rule bases its results on the properties of a unidirectional lamina. Depending on the fibre direction the actual stiffness is calculated by adding a factor, λ. For a 0‐degree fibre direction this factor is set to 1 and for 45° and 90° fibre angles the factor is set to 0.1 (this explains the name of the rule). Experience has shown that this factor gives results that agree relatively well to reality. However the method is not designed to be applied on CSM‐mats. espite this, the 10%‐ rule is still applied on stiffness calculations of CSM‐fibre. This could well D
be a source of error. The Rule of Mixtures method could be regarded as more accurate than the 10% rule since it analyses the fibre and matrix separately. To calculate the fibre stiffness for a particular angle a einforcement efficiency factor is introduced β. The factor takes into account the amount of rfibres that are effective in the direction of interest. By comparing the results of the two different methods, Table 1, one can realize that they give very similar stiffness values for 0‐ and 90 degree fibre directions. The 10% rule seems to generate slightly lower values, i.e. more conservative results. However, for a fibre angle at 45 degrees the methods generate completely different numbers.