The experimental results from the blocks loading fatigue tests are compared with the predictions using the proposed model and Miner's rule. Estimated and experimental results are found to exhibit good agreement. The evaluation technique of the K I stress intensity factors (SIF) by a numerical investigation using line strain method is developed. The main purpose of this research is to estimate experimental results of fracture loads from polymethyl-metacrylate (PMMA) specimens (fully finite plates). Stress intensity factor equation calculation is derived from the Williams stress asymptotic expansion. Computed values using finite element analysis of stress intensity factors are compared with the experimental and theoretical results. A good agreement is observed between the present approach and experimental data. It is shown that, in the case of a through-plate crack, the stress intensity factor can be measured with a good accuracy using the proposed method.