Fatigue crack growth tests are conducted to assess the efficacy of the stop-hole crack repair method. This straightforward and widely adopted technique involves drilling a hole at the crack tip and subsequently enlarging it using a pin inserted into the hole. A fracture mechanics-based model is proposed to estimate the extension of fatigue life achieved through the implementation of the stop-hole technique. The model’s predictions are validated using data obtained from fatigue crack growth tests conducted on both unrepaired and repaired M(T) specimens, following the guidelines outlined in the ASTM E647 standard. The error of the fracture mechanics-based model was 1.4% in comparison with the fatigue tests.

Analytical (closed-form) solutions are developed for the deflections and rotations of thick specially orthotropic plate twist specimens by using first-order shear deformation theory. Results are compared with outcomes from finite element method, previously reported experiments, and a classical laminated plate theory solution. A [(0/90)₆]_s cross-ply laminate and a sandwich panel with aluminum face sheets and a polyvinyl chloride (PVC) foam core are used as baseline materials. Overall, good agreement between first-order shear deformation theory and finite element method is obtained for compliance predictions. It is found that the proposed first-order shear deformation theory approach can be used to adequately calculate the deflections of specially orthotropic plates from low to moderately high side length to thickness ratios [ ]. Examination of the in-plane shear modulus ratio between face sheets and core ([ ]) points out that first-order shear deformation theory slightly underpredicts the compliance with respect to finite element method, specially for [ ] ratios larger than 100. Both solutions based on plate theories are suitable to estimate the compliance of cross-ply laminates with moderate [ ] ratios ([ ]). First-order shear deformation theory is able to properly predict the compliance of square and rectangular laminates with aspect ratios lower than 10. Good agreement between published compliance measurements and those predicted by first-order shear deformation theory is found for Maple plywoods, monolithic metals, and specially orthotropic sandwich panels.

Islas Huichas, located in Chile’s remote Aysén region, has long faced water scarcity due to a lack of natural sources. The community relies on rainwater collection pools managed by the Rural Drinking Water Committee (RDWC), which face increased pressure during the summer tourist season, leading to frequent shortages. In 2014, a Reverse Osmosis (RO) plant with a 240 m³ daily capacity was installed to address the issue. While the RO plant helps alleviate summer shortages, it has high energy costs and maintenance challenges, exceeding the financial capacity of the RDWC. This study evaluates various scenarios to reduce the plant’s operational costs and emissions reduction.

The shear stress on isotropic curved beams with compact sections and variable thickness is investigated. Two new solutions, based on Cook’s proposal and the mechanics of materials approach, were developed and validated using computational finite element models (FEM) for four typical cross-sections (rectangular, circular, elliptical, and triangular) used in civil and mechanical structures, constituting a novel approach to predicting shear stresses in curved beams. They predict better results than other reported equations, are simpler and easier for engineers to use quickly, and join the group of equations found using the theory of elasticity, thereby expanding the field of knowledge. The results reveal that both equations are suitable to predict the shear stress on a curved beam with outer/inner radii ratios in the interval $1<b/a$ ≤ 5 aspect ratios. There is a maximum relative difference between the present solutions and finite element models of 8% within $1<b/a$ ≤ 2, and a maximum of 16% in $2<b/a$ ≤ 5. Additionally, the neutral axis of the curved beam can be located with the proposed solution and its position matches with that predicted by FEM. The displacement at the top face of the end of the curved beam induces a difference in the shear stress results of 8.0%, 7.0%, 6.5%, and 2.9%, for the circular, rectangular, elliptical, and triangular cross-sections, respectively, when a 3D FEM solution is considered. For small $b/a$ ratios (near 1), the present solutions can be reduced to Collignon’s formula.