Optimal design and testing of laminated light-weight composite structures with local reinforcements considering strength constraints: Part II: Testing

The present paper explains details of the measurement methods applied in the testing of strength-optimized locally reinforced laminates whose design has been explained in Part I. The measurement methods are an optical surface method, based on Digital Image Correlation (DIC), and measurements of Acoustic Emission (AE) which can originate from anywhere within the test specimen. Both methods are intended to identify early damage events or accumulation and the corresponding loads are compared to predicted first-ply-failure loads. The DIC method identifies non-linearities in the displacement path which infer that damage events have occurred. The AE method utilizes the signal energy rate per time to identify damage events. The results of the particular specimens show no correlation between the two measurement methods. The averaged values for the different type specimens show a significant dependency.