This paper demonstrates that the crack‑growth rate under non‑proportional loading can be effectively characterized using a relatively simple stress indicator, the synthetic stress amplitude. The experimental results are presented in a clear and concise manner, giving the impression that the authors have organized their findings very effectively.
The study also proposes a practical method for predicting crack‑growth life that does not require the use of digital image correlation, which is often labor‑intensive. By estimating the effective synthetic stress range solely from non‑proportional loading conditions and predicting crack‑growth life using the proposed formula, the method appears feasible for engineers to apply in practice. It is also commendable that the evaluation metrics and predictive expressions are formulated to minimize the use of material‑specific parameters.
If engineers were to use the prediction method proposed in this paper, it would likely be in maintenance operations. For example, during routine inspections, a crack may be found in equipment that is otherwise operating normally. In such cases, the equipment is subjected to highly complex loads during operation, and engineers must determine whether the crack will continue to grow and, if so, when repairs should be scheduled.
On the other hand, in design and development work, strength design is generally not performed based on crack‑growth life, so the proposed method may not be directly necessary for that context.

This paper focuses on the adhesive joints of wind turbine blades and proposes a model for predicting their fatigue life while accounting for the influence of multiple environmental factors. Considering the combined effects of temperature, aging, and salt concentration is a challenging task, and the successful development of a model that integrates all of these elements reflects a high level of research sophistication.The study also presents an innovative approach by noting that fatigue damage accumulates in two stages and introducing a Wiener model to explain this behavior.

On the other hand, some of the photographs and figures appear rather small, and the information provided on the plate materials and adhesives used in the test specimens seems somewhat limited. In particular, although the plates appear to be made of carbon‑fiber‑reinforced plastics, such materials are generally not used for wind turbine blades, which are typically reinforced with glass fibers.

Additionally, the loads acting on actual blades are variable‑amplitude loads, rather than the constant‑amplitude loads considered in this paper. It would be interesting to see whether the proposed model could also be applied under variable‑amplitude loading conditions.

This paper aims to obtain material properties essential for designing the seismic performance of high‑rise buildings. Specifically, it investigates the cyclic behavior of SN490B, a structural steel commonly used as a primary material in tall buildings, through material tests conducted under complex loading conditions. The testing approach employed in this study—multiaxial strain‑controlled experiments using extensometers—is relatively advanced, and the successful implementation of such methods is commendable.
At the same time, the amount of experimental data presented appears somewhat limited. It would be interesting to see whether other major construction materials exhibit cyclic characteristics similar to those of SN490B, and I look forward to future research developments in this area.