The paper explores enhancing the mechanical behavior of stochastic lattice structures through a semi-controlled design approach. By leveraging the Gibson-Ashby model and predefined geometric routines, the study aims to optimize the mechanical response of lattice structures under compressive stress. Transitioning from stochastic to semi-controlled tessellation using Rhinoceros 7 software enables more predictable deformation behavior. Design parameters such as node formation, strut thickness, and lattice generation patterns are correlated with relative density to regulate stiffness and strength. Experimental validation using Acrylic Styrene Acrylonitrile (ASA) filament demonstrates the effectiveness of the proposed design model. The research emphasizes the importance of understanding internal mechanics by introducing a novel design approach to control geometry and topology arrangement in shaping lattice properties. By introducing a semi-controlled mechanism, the study seeks to improve the reliability and uniformity of mechanical responses in lattice structures. The findings highlighted the benefits of semi-controlled design approaches in achieving tailored mechanical properties. Specimens were compression tested in quasi-static uniaxial loading and showed that structures created with parabolic distribution dimensioned by ${\mathrm{h}}_{\mathrm{p}}=0.5{\mathrm{h}}_{\mathrm{v}}$ originated the most reliable and most vital mechanical response compared with other design models, including typical Voronoi distribution. The improved mechanical response in between proposed design models constantly progressed by about 15% on average consecutively, starting from the parabolic distribution dimensioned by ${\mathrm{h}}_{\mathrm{p}}=1.0{\mathrm{h}}_{\mathrm{v}}$ as the weakest ranked, up to the best one, dimensioned by ${\mathrm{h}}_{\mathrm{p}}=0.5{\mathrm{h}}_{\mathrm{v}}$, even better than the typical Voronoi distribution. The proposed design model has introduced an entirely novel approach that significantly enhances the product’s volume tessellation using routines that guarantee the validity of geometric and topologic entities. Uniaxial compression tests on lattice blocks highlighted the effect of the proposed approach on the mechanical properties of these structures, having shown particularly crucial repeatability and stability. Overall, the paper contributes to advancing the field of lightweight lattice structures through the novel design methodology and material characterization.

Research show that the vibrations of the strings and the radiated sound of the solid body electric guitar depend on the vibrational behavior of its structure in addition to the extended electronic chain. In this regard, most studies focused on the vibro-mechanical properties of the neck of the electric guitar and neglected the coupling of the vibrating strings with the neck and the solid body of the instrument. Therefore, the aim of the study was to understand how the material properties of the solid body could affect the stiffness and vibration damping of the whole instrument when comparing ash (Fraxinus excelsior L.) and walnut (Juglans regia L.) wood. In the electric guitar with identical components, higher modal frequencies were confirmed in the structure of the instrument when the solid body was made of the stiffer ash wood. The use of ash wood for the solid body of the instrument due to coupling effect resulted in a beneficial reduction in the vibration damping of the neck of the guitar. The positive effect of the low damping of the solid body of the electric guitar made of ash wood was also confirmed in the vibration of the open strings. In the specific case of free-free vibration mode, the decay time was longer for higher harmonics of the E₂, A₂ and D₃ strings.

During the process of defining suitable design solutions, a designer has to consider a wide range of influential factors. Ergonomics certainly belongs to more complex ones. Less experienced designers could encounter several problems during this design stage. Although some literature can be found about ergonomic design of hand tools, a designer still has to have amassed quite a lot of experience and knowledge in the field of ergonomic, in order to choose and carry out appropriate design and redesign actions. Existing computer tools for ergonomic design are not able to assist a designer with higher level advice within design process. An intelligent decision support system has been developed in order to overcome this bottleneck. This paper presents a knowledge base, containing ergonomic design knowledge specific for hand tools design. A pneumatic hammer handle design is used as a case study to show how ergonomic design knowledge built in the system is used to improve the ergonomic value of the product

When considering product handle ergonomics, authors have focused on product handle sizes and shapes, while handle materials have been largely ignored. Authors have shown that handles coated with rubber foam were more comfortable than stiff handles. However, they did not provide detailed material properties, nor did they investigate different stiffnesses and their impact on tactile perception during grasping. Therefore, in this article, we investigated the influence of product interface material stiffness using a common wood sawing task with a saw handle made of hard plastic and 3D-printed deformable material with different stiffnesses. The results showed that user tactile perception can be improved significantly where the 3D-printed cellular density, and, hence material stiffness, has a significant influence on the resulting tactile perception. However, results have shown that the material stiffness must be determined appropriately to maintain the stability of the products in hands. The results also suggest that the product interface material had a greater influence on the reported overall comfort rating than the product handle shape in the sawing task.