Weibull modulus

Weibull modulus is a measure of the distribution of flaws usually for a brittle material. The modulus is a dimensionless number corresponding to the variability in measured strength and reflects the distribution of flaws.

For example, consider strength measurements made on many samples of a brittle material, such as ceramic. If the measurements show little variation from sample to sample, the Weibull modulus will be high and the average strength of the material would be a good representation of the potential sample-to-sample performance of the material. The material is consistent and flaws -- due to the material itself or the manufacturing process -- are distributed uniformly throughout the material. A low Weibull modulus reflects a high variation in measured strengths and a likelihood that flaws would tend to congregate and produce a weaker material. A material with a low Weibull modulus will more likely exhibit samples where the strength is substantially below the average and therefore show greater inconsistency and probably less reliable.

Test procedures for determining the Weibull modulus are specified in DIN EN 843-5 and DIN 51 110-3.