This paper presents a new way to design a broadband harvester for harvesting high energy over a low-frequency range of 10–15 Hz. The design comprises a cantilever beam with two parallel grooves to form three dissimilar length parallel branches, each with an unequal concentrated tip mass. The piezoelectric material covers the whole length on both sides of the beam to form a bimorph. Appropriate geometry and mass magnitudes are obtained by a parametric study using the Finite Element Method. The design was simulated in COMSOL Multiphysics to study its response. The first three bending modes were utilized in energy harvesting, resulting in three power peaks at their respective fundamental frequencies. The adequate load resistance determined was 5.62 kΩ, at which maximum power can be harvested. The proposed harvester was compared to two other harvesters presented in the literature for validation: First, an optimized conventional harvester while the proposed harvester is operating at adequate load resistance. Second, a multimodal harvester, while the proposed harvester is operating at a 10 kΩ load. The suggested harvester proved to be more efficient by harvesting sufficiently higher broadband energy and is applicable in a wide range of vibration environments because of its adaptability in design.

Crash boxes play a vital role in improving vehicle safety by absorbing collision energy and reducing the forces transmitted to occupants. Additive manufacturing (AM) has become a powerful method for developing advanced crash boxes by enabling complex geometries. This review provides a comprehensive examination of recent progress in AM crash boxes, with a focus on three key aspects: geometric design innovations, material behavior, and manufacturing techniques. The review investigates the influence of various AM-enabled structural configurations, including tubular, origami-inspired, lattice, and bio-inspired designs, on crashworthiness performance. Among these, bio-inspired structures exhibit superior energy absorption characteristics, achieving a mean specific energy absorption $\left(SEA\right)$ of 21.51 J/g. Material selection is also explored, covering polymers, fiber-reinforced polymers, metals, and multi-material structures. Metallic AM crash boxes demonstrate the highest energy absorption capacity, with a mean $SEA$ of 28.65 J/g. In addition, the performance of different AM technologies is evaluated, including Stereolithography (SLA), Material Jetting (MJT), Selective Laser Melting (SLM), Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM), and hybrid manufacturing techniques. Among these, crash boxes produced by SLM show the most favorable energy absorption performance, with a mean $SEA$ of 16.50 J/g. The findings presented in this review offer critical insights to guide future research and development in the design and manufacturing of next-generation AM crash boxes intended to enhance vehicle safety.

Crash boxes play a crucial role in automotive safety by absorbing impact energy during collisions. The advancement of additive manufacturing (AM), particularly Fused Deposition Modeling (FDM), has enabled the fabrication of geometrically complex and lightweight crash boxes. This study presents a comparative evaluation of the crashworthiness performance of five FDM materials, namely, PLA+, PLA-ST, PLA-LW, PLA-CF, and PETG, across four structural configurations: Single-Cell Circle (SCC), Multi-Cell Circle (MCC), Single-Cell Square (SCS), and Multi-Cell Square (MCS). Quasi-static axial compression tests are conducted to assess the specific energy absorption $\left(SEA\right)$ and crush force efficiency $\left(CFE\right)$ of each material–geometry combination. Among the materials, PLA-CF demonstrates superior performance, with the MCC configuration achieving an $SEA$ of 22.378 ± 0.570 J/g and a $CFE$ of 0.732 ± 0.016. Multi-cell configurations consistently outperformed single-cell designs across all materials. To statistically quantify the influence of material and geometry on crash performance, a two-factor ANOVA was performed, highlighting geometry as the most significant factor across all evaluated metrics. Additionally, a comparative test with aluminum 6063-T5 demonstrates that PLA-CF offers comparable crashworthiness, with advantages in mass reduction, reduced $PCF$, and enhanced design flexibility inherent in AM. These findings provide valuable guidance for material selection and structural optimization in FDM-based crash boxes.

This study focuses on the role of the damage evolution when estimating the failure behavior of AISI 1045 steel for sensing and measuring metal cutting parameters. A total of five Lagrangian explicit models are established to investigate the effect of applying damage evolution techniques. The Johnson–Cook failure model is introduced once to fully represent damage behavior, i.e., no damage evolution is considered, and as a damage initiation criterion in the remaining approaches. A fracture energy-based model is included to model damage propagation with different evolution rates. Temperature-dependent and temperature-independent fracture energy models are also investigated. Dry orthogonal cutting and residual stresses measurements of AISI 1045 are conducted for validation. The significance of the damage evolution is investigated using honed-tool and sharp-tool models. Including the damage evolution led to a prediction of higher workpiece temperatures, plastic strains, cutting forces, and residual stresses, with no clear differences between linear and exponential evolution rates. The role of damage evolution is more evident when temperature-dependent evolution models are used.

This paper investigates a new external fixator system for treating finger contractures. This innovative system is electric and user-friendly, providing precise readings of the angles of diseased finger joints. Accurate measurements of the angles of the diseased finger joints can assist therapists and patients during rehabilitation procedures. The fixator consists of ten parts assembled using polyether-ether-ketone (PEEK) for the plastic components and stainless steel for the metal components. The design model was engineered, drawn, and analyzed using SolidWorks Computer-Aided Design software. The verification process utilizes finite element analysis to demonstrate that the maximum stress was lower than the yield strength of the chosen materials. As a result, the new device design is robust and stable enough to withstand the anticipated loading conditions of human fingers. Subsequently, a prototype was fabricated using advanced additive manufacturing technology, specifically fused deposition modeling (FDM). The proposed fixator is simple to control, reliable, easy to use, and reproducible. It enables device users to exercise their finger joints throughout the day without requiring the assistance of specialists.