Journal of Biomimetics, Biomaterials and Biomedical Engineering Vol. 73

Abstract: The mandible is a part of the head that plays an important mechanical role, especially in activities such as chewing and speaking. Due to its prominent position and functional activity, this bone is prone to injury from accidents. In its treatment, mandibular implants are commonly used; however, structural failure often occurs due to design mismatches with physiological loading conditions. Therefore, this study conducted a Finite Element Analysis (FEA) simulation on mandibular implants made of Ti-6Al-4V material manufactured using the Bound Metal Deposition (BMD) method. The simulation aimed to analyze stress distribution, deformation, and safety factors across various implant designs by varying the number and position of support holes, as well as cortical thickness. A total of nine implant variations were tested, consisting of two, four, and six screw hole configurations arranged in vertical, zig-zag, and inclined patterns. Cortical thicknesses of 0.8 mm, 1.0 mm, and 1.2 mm were also analyzed to evaluate their influence on implant strength, under axial loading with forces of 100 N (representing chewing force) and 800 N (maximum mandibular load capacity). The simulation results showed that the six-hole variation in Model 2 produced a safety factor of 3.05 under 100 N axial load, but significantly dropped to 0.38 under the 800 N load, indicating a high risk of fracture. On the other hand, the cortical thickness of 1.2 mm showed the best performance, achieving a safety factor of 15.00 under 100 N and 2.25 under 800 N axial load. Therefore, the combination of an inclined hole configuration and 1.2 mm cortical thickness is recommended as the strongest mandibular implant design based on this numerical analysis.

Abstract: With the development of intelligent driving technology, there are more and more complaints about motion sickness from passengers in autonomous vehicles. A precise tool is needed to measure ride comfort. This paper proposes a motion sickness estimation method that combines vehicle dynamics with human factors. It integrates the six-degree-of-freedom SVC model into a comprehensive human-car interaction framework. Real-world experiments collected relevant data from in-vehicle tests, the average accuracy rate of head linear acceleration prediction is 89.1%, and the accuracy rate of angular velocity prediction is 84.6%. The heart rate variability data and participant feedback are consistent with the model prediction. This consistency means the method can capture real passenger motion perception. It helps to improve the ride comfort of autonomous driving.

Abstract: Rotary endodontic instruments are extensively utilized in root canal procedures for the removal of infected pulp tissue. These instruments are typically fabricated from nickel–titanium (NiTi) alloy, which possesses superelastic properties that enable effective navigation through curved root canals. Nevertheless, this superelasticity hinders the early detection of fatigue or fracture, thereby elevating the risk of instrument failure during clinical use. The present study aims to assess the axial stress, strain, total deformation, and fatigue life of the ProTaper Next X2 rotary endodontic file and its modified designs through the application of the finite element method (FEM). The instruments were redesigned using computer-aided design (CAD) software and subsequently analyzed with ANSYS simulation software. Evaluation parameters included von Mises stress, strain distribution, total deformation, and fatigue life. The findings were employed to compare the original and modified designs to determine an optimal structural configuration for rotary endodontic instruments.