Abstract
Indentation fracture is a commonly employed technique for investigating solids' material properties and response to indentation. Subsurface lateral cracks are related to the mass lost on materials presenting brittle behaviour, and these cracks are usually observed in indentation experiments performed above critical loads. In this study, five microindentations were superimposed to evaluate the formation of lateral cracks under low loads, lower than the critical load, on soda-lime glass. Experimental tests were carried out using a standard Vickers indenter for individual indentations, revealing that radial cracks appeared for indentation forces greater than 98 mN. In comparison, lateral cracks only manifested for indentation forces exceeding 980 mN. To further investigate this phenomenon, we performed superimposition tests, consisting of seven lines, each containing five indentations. The indentation load ranged from 200 mN to 1000 mN, with varying relative distances between indentations in subsequent lines, thereby controlling the superimposition index from − 200–90%. Our findings established a direct correlation between crack formation, the degree of superimposition, and the indentation load. A single indentation performed with a load below the critical threshold did not generate sufficient stress to initiate lateral crack formation. However, with the superimposition of indentations, the interaction of the residual stress field near the previous indentation imprints induced lateral cracks even with loads five times lower than the critical threshold. These insights contribute to a deeper understanding of the mechanics involved in indentation-induced crack formation in brittle materials, with potential implications for material science and engineering applications.