Figure 1 Product filled with oblong re-used material elements


Effective modulus of elasticity:


(based on parallel model) Effective tensile strength:


Ec σc


≈ vr ≈ vr


· Er · σr


+ vm · Em (1) (2) In formulas 1 and 2 the volume fractions of the components are used, indicated with the symbol ‘v’.


The performance of new products consisting of re-used composite elements depends on the length of the embedded oblong elements. An extensive study has been performed on the effect of length, positioning and pre-treatment of the elements by three-point bending tests [4].


It was found that the bending strength of a profile built from strips increases with the strip length as depicted in Figure 2.


250 200 150 100 50 0 0 200 400 600 Length of reinforcing elements (mm) Figure 2 - Bending strength as function of strip length 54 | The Report • September 2017 • Issue 81 800 1000 Strips laid flat-wise Shredded


Bending strength (MPa)


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