Mechanoluminescent (ML) sensor consisting of polymer and functional ceramic powder (SrAl₂O₄:Eu²⁺) emits intensive green light repeatedly accompanied by mechanical stimulation even in elastic defamation region. The ML intensity is proportional to Mises strain energy. Thus, when dispersedly coated onto a structure, each particle acts as a sensitive mechanical sensor, while the two-dimensional (2D) emission pattern of the whole assembly reflects the dynamical strain/stress distribution. Actually, we have successfully visualized (1) a crack existing, generation and propagation in structural health monitoring (SHM), (2) strain distribution in 3D designed industrial parts such as car body and various joints for light weighting. In addition, we introduce recent mechanoluminescent studies on evaluating functional degradation of structural materials, such as (3) detection of plastic defamation area, (4) CFRP (carbon fiber reinforced plastic) (5) delamination of dissimilar material adhesive joint and functional recovering for circular economic industries.