Evaluation Of Mechanical Integrity Research Articles

Probing Physicochemical Performances of 3D Printed Carbon Fiber Composites During 8‐Month Exposure to Space Environment

AbstractCarbon fiber reinforced polymers (CFRPs) offer exceptional properties that make them highly relevant in the aerospace industry, such as high thermal conductivity and an outstanding strength‐to‐weight ratio. Advances in additive manufacturing have expanded the aerospace applications of CFRPs, even allowing for in‐space fabrication of complex structures. Understanding the stability of CFRPs in the harsh conditions of low Earth orbit (LEO) is crucial. LEO exposes materials to extreme environmental factors, such as vacuum, radiation, atomic oxygen, and temperature fluctuations, which can accelerate degradation. To investigate the space‐environment effect on material, changes in properties of 3D‐printed CFRPs are compared with CFRPs made through forging and conventional compression molding. Surface analyses examine morphological, chemical, and matrix composition changes, along with an evaluation of mechanical integrity. Remarkably, the naked 3D printed CFRPs withstood 8 months of LEO exposure similar to the compression molded CFRP samples, with changes in chemical properties limited to the sample's outer surface. Further, despite no protective coatings are used, limited surface erosion and no variation in mechanical strength are observed. These results provide relevant information for the development and deployment of novel 3D printed CFRPs materials for a wide spectrum of terrestrial and space applications.

Evaluation of mechanical integrity on the brazing joint of a tube-type heat exchanger with considering local material properties

Recently, the demands for eco-friendly and effective energy systems have rapidly increased due to global environment problems. A heat exchanger is a well-known mechanical rig that has been used for a long time in many energy systems to reduce heat energy loss and to increase energy efficiency. However, till now, there have been few attempts to install a heat exchanger inside of an airliner engine. In such a case, the heat exchanger should be designed to be compact, lightweight, and highly reliable; therefore, the issue of the mechanical integrity of the heat exchanger becomes very important. In this study, we suggest a method by which it is possible to evaluate the mechanical integrity of a tube-type heat exchanger using global and local analysis. In the global analysis, fluid–structure interaction was introduced to get global behavior of a tube, which was used as boundary conditions in the local analysis. Also, local material properties near a brazing joint were measured using a nano-indentation test, and then they were utilized in the local analysis to evaluate clearly stress distribution around the joint. Through this study, a U-shaped single tube brazed on a manifold, which is a segment of a tube-type heat exchanger, was used as an example; its fatigue limit and stress concentration on the joint depending on the change of fillet radius were estimated by the proposed approach.

711 耐摩耗被膜の破壊挙動と総合的機械特性に基づく新しい健全性評価

711 耐摩耗被膜の破壊挙動と総合的機械特性に基づく新しい健全性評価