Foldable displays represent one of the most attractive next-generation display applications. Therefore, it is critical to analyze the effects of mechanical stress on amorphous InGaZnO (a-IGZO) thin-film-transistors (TFTs) in order to apply them to foldable displays. In foldable display applications, the dynamic mechanical stress tests are designed to be carried out using a bending radius of less than 3 mm. In this paper, dynamic mechanical bending stress tests are performed on a-IGZO TFTs using various bending radii and directions in order to examine the instability characteristics of the TFTs. In addition, the degradation mechanisms are investigated using a technology computer-aided design simulation. As a result, we have demonstrated that it is now possible to establish reliable circuit guidelines for using a-IGZO TFTs in foldable display applications.