Fatigue behaviour of T-joints for marine applications

et al. 2020

Applied Sciences

Wind turbines are under continuous development for large-scale deployment and oceanization, leading to the requirement of longer blades. The economic losses caused by blade replacement and shutdown have increased. The downtime caused by blade issues in a wind turbine is 8-20% of the total downtime. Many of these blade issues originate from the cracking of the blade trailing edge. The edge is more susceptible to damage due to the complex geometry, manufacturing technique, and operation conditions. The traditional design method and the expensive experimental research are not suitable for the accurate damage analysis of the trailing-edge adhesive because of simplifying assumptions and costs. This study aimed to investigate the influence of trailing-edge structural configurations on the shear fatigue life of the trailing-edge adhesive joint using finite element and stress transformation matrix (STM) methods. The structural configurations of the blade trailing edge included the position of unidirectional fiber layer (UD), chamfer of bonding line, prefabricated components, and outer over-lamination of the trailing edge. In this study, the finite element method was used to simulate the blade structure. The shell element was used for laminates, and the solid element was used for the trailing-edge adhesive joint. The basic shear fatigue properties of the adhesive were obtained by standard component tests. The shear fatigue life of the blade trailing-edge adhesive joint under given load conditions was calculated using the fatigue properties of the adhesive and STM method. The results showed that the angle of chamfering, location of UD, rigidity of the preform, and outer over-lamination all had an obvious influence on the fatigue damage of trailing-edge adhesive. The findings of this study can be used to guide blade structure design and blade production and maintenance.

Section: Introductionmentioning

confidence: 99%

Influence of Structural Configurations on the Shear Fatigue Damage of the Blade Trailing-Edge Adhesive Joint

Chen

et al. 2020

Applied Sciences

“…Failure of composite T-joints has also been studied experimentally from different point of view by many investigators [3,4,[20][21][22][23][24][25][26][27][28][29]. The initiation of delamination in the composite T-joint is almost always initiated on the joint's corner due to the maximum stresses developed in this region.…”

Section: Introductionmentioning

confidence: 99%

A Finite Element and Experimental Analysis of Composite T-Joints Used in Wind Turbine Blades

Soutis

2018

Appl Compos Mater

In this study, a finite element failure model was created using ABAQUS to determine the location where delamination is initiated and its subsequent propagation. The effect of fibre-reinforced structures on delamination behaviour was studied. The composite Tjoints were made of glass fabric infused with epoxy resin using a vacuum assisted resin transfer moulding technique. The veil layer and 3D weave techniques were employed to improve the properties in the through-thickness direction that can delay or prevent delamination when in service. All the pull-out tensile tests were conducted in an Instron testing machine using a specially designed test fixture. The 3D weave T-joints were found to have improved performance under both static and fatigue loading. Increasing the static properties increases fatigue life performance. The location for the through-thickness reinforcement plays an important role in extending fatigue life of the T-joints.

“…With the rapid developments in computing capacity of computer, 3D FE models, which can characterize the 3D nature of structural stresses [29], attract more attentions in adhesively bonded joints. The 3D FE models are not only suitable for simulation of complex structural configuration [30 -38] but also effective to obtain more accurate stress distribution and reveal the transverse stress effects [29,39]. However, the modelling process is perplexing and exhaustive at time cost to those who are short of professional knowledge.…”

Section: Introduction *mentioning

confidence: 99%

A New Material Model for 2D FE Analysis of Adhesively Bonded Composite Joints

Zhao

Qin

et al. 2014

Effective and convenient stress analysis techniques play important roles in the analysis and design of adhesively bonded composite joints. A new material model is presented at the level of composite ply according to the orthotropic elastic mechanics theory and plane strain assumption. The model proposed has the potential to reserve nature properties of laminates with ply-to-ply modeling. The equivalent engineering constants in the model are obtained only by the material properties of unidirectional composites. Based on commercial FE software ABAQUS, a 2D FE model of a single-lap adhesively bonded joint was established conveniently by using the new model without complex modeling process and much professional knowledge. Stress distributions in adhesive were compared with the numerical results by Tsai and Morton and interlaminar stresses between adhesive and adherents were compared with the results from a detailed 3D FE analysis. Good agreements in both cases verify the validity of the proposed model.