2023 Volume 49 Issue 2 Pages 57-69
A method for estimating the elastic properties of random oriented chopped UD tape reinforced thermoplastic composites (CTT) containing different UD tape lengths from in-plane strain distributions obtained in tensile tests was investigated using 3D-DIC analysis. The probability density function (PDF) and autocorrelation function of the in-plane strain distribution of 100 MPa were obtained. The elastic modulus was measured from nominal stress-strain data. The difference of the mean value of the theoretically calculated elastic modulus from the gauge length made dimensionless by the autocorrelation length indicates that the PDF of the in-plane strain distribution is correlated with the elastic modulus properties. The probabilistic properties of the elastic modulus distribution obtained at each point on the specimens were examined, revealing that the obtained result depended not only on the size of the measurement section but also on the data processing method. The elastic modulus of CTT must be defined as a constant value at the limit of the gauge length and the number of samples, and it was shown that it is appropriate to define it as the reciprocal of the stochastic convergence value of elastic compliance for general specimens with small width.
