Abstract: In many fields such as aerospace, petrochemical and energy power, the contradiction between the need for long-life and high-reliability of critical mechanical equipment and their harsh service environment is increasingly evident. On the one hand,single-damage-driven or single-failure mode-driven life design methods can not cover multiple damage interaction modes and multi-scale damage characteristics at the current stage. On the other hand, classic continuum damage theory is not well suited to the needs of engineering design. In order to improve the engineering applicability and universality of damage theory, on the basis of revealing the degradation of material properties and load variations, the engineering damage theory based on the essential safety of mechanical structures is expected to achieve accurate life design by establishing the cumulative damage-damage threshold interference principle. It also evaluates the damage state and remaining life of mechanical equipment in service to facilitate the operation and maintenance management of mechanicalsystems. This paper introduces the scientific connotation of engineering damage theory, organizes the historical developments and looks into the future research challenges. In response to the three core principles of engineering damage theory, this paper focuses on a review of research advances in damage testing techniques for mechanical property degradation, damage evaluation methods considering multi-mechanism interactions, and application carriers for engineering objects. In the era of big data, this paper introduces the opportunities and challenges of engineering damage theory in the direction of life management development. It is expected to realize the in-depth integration between data driven and physical damage,and to break through the technical closure bottleneck challenges of monitoring science-equipment science-damage theory-information science-health management for key engineering mechanical equipment.

Key words: engineering damage theory, damage testing, software integration, reliability assessment, health management