## 1 Introduction  
Composite blades are engineered for a lifespan exceeding 25 years and often fail prematurely during operation. Addressing this issue necessitates a methodology to elucidate and monitor the progression of debonding damage in the adhesive joint area, a critical defect in blades. This approach should identify the specific failure mechanisms. Wind turbine composite blades, in particular, incorporate uniaxial, biaxial, and triaxial composite materials in their upper and lower skins and shear webs to balance lightness and load-bearing capacity, thereby enhancing structural performance. The performance of these hybrid composites varies, as they are tailored to offset the limitations of each laminated composite's properties [1, 2]. The design strategy evaluates the mechanical properties of each material, but the failure characteristics of hybrid composites may differ from single materials [3]. Recent research has focused on the occurrence and progression of debonding damage. [PERSON] et al. [4] identified cracks in the trailing edge (TE) through specimen tests and theoretical analysis. [PERSON] et al. [5] and [PERSON] et al. [6] offered methods for detecting and assessing internal debonding and delamination in wind blades. Notably, [PERSON] et al. [7] conducted debonding analyses for wind blade T-Joints, and [PERSON] et al. [8] devised a failure dynamics method for joint damage, using cohesive zone modeling (CZM) for the spar-web joint and mode II sliding mode test data. However, the TE and leading edge (LE) adhesive joints, vital for bonding suction and pressure sections, also present vulnerabilities [9; 10; 11; 12], underscoring the need for their examination in prior studies. Accurate evaluation and prediction of blade joint debonding damage necessitate comprehensive test data for mode I (double cantilever beam, DCB), mode II (end-notched flexure, ENF), and mixed mode (mixed mode bending, MMB), along with the validation of material properties based on these testing techniques [13; 14; 15]. Debonding damage in wind turbine blades' adhesive joints arises from external loads, necessitating a thorough examination of the loads impacting the turbine. Wind conditions and environmental factors contribute to operational loads, subjecting the blades to combined stresses. Studies indicate that these combined loads significantly compromise blade structural integrity more than unidirectional loading [16]. Therefore, analyzing debonding damage under these combined load conditions is essential. Adhesive joint modeling in wind turbine blades offers an efficient method for failure mechanism analysis, yet it often relies on predefined assumptions about damage mechanisms. For instance, [PERSON] and [PERSON] [17] applied a cumulative fatigue damage model to simulate blade fatigue damage. They first conducted static analysis to pinpoint risk positions, particularly on the upper flange of the blade support unit, followed by fatigue crack growth analysis at these critical points. Similarly, [PERSON] et al. [18] undertook a numerical analysis of blades under static bending and torsional loads to identify stress-prone areas, revealing the root section and TE as particularly vulnerable. Various analytical methods and accident reports underscore the need for a comprehensive understanding of factors influencing blade damage, including operational conditions, location, weather, and manufacturing processes. However, such analyses often overlook discrepancies between design and operational conditions. Notably, the state of blades that are 10, 15, or 20 years old differs significantly from those produced currently in terms of materials, quality control, technology, and size. Full-scale testing of wind turbine blades in a laboratory during the design phase is typically feasible only for smaller turbines and does not accurately reflect real-world operating conditions.