Triply periodic minimal surfaces (TPMSs) constitute a type of metamaterial, deriving their unique characteristics from their microstructure topology. They exhibit wide parameterization possibilities, but their behavior is hard to predict. This study focuses on using an implicit modeling method that can effectively generate novel thin-walled metamaterials, proposing eight shell-based TPMS topologies and one stochastic structure, along with the gyroid acting as a reference. After insights into the printability and design parameters of the proposed samples are presented, a cell homogeneity analysis is conducted, indicating the level of anisotropy of each cellular structure. For each of the designed metamaterials, multiple samples were printed using a stereolithography (SLA) method, using a constant 0.3 relative density and 50 µm resolution. To provide an understanding of their behavior, compression tests of sandwich-type specimens were performed and specific deformation modes were identified. Furthermore, the study estimates the general mechanical behavior of the novel TPMS cores at different relative densities using an open cell mathematical model. Alterations of the uniform topologies are then suggested and the way these modifications affect the compressive response are presented. Thus, this paper demonstrates that an implicit modeling method could easily generate novel thin-walled TPMSs and stochastic structures, which led to identifying an artificially designed structure with superior properties to already mature topologies, such as the gyroid.

Sandwich structures with triply periodic minimal surface (TPMS) cores have garnered research attention due to their potential to address challenges in lightweight solutions, high-strength designs, and energy absorption capabilities. This study focuses on performing finite element analyses (FEAs) on eight novel TPMS cores and one stochastic topology. It presents a method of analysis obtained through implicit modeling in Ansys simulations and examines whether the results obtained differ from a conventional method that uses a non-uniform rational B-spline (NURBS) approach. The study further presents a sensitivity analysis and a qualitative analysis of the meshes and four material models are evaluated to find the best candidate for polymeric parts created by additive manufacturing (AM) using a stereolithography (SLA) method. The FEA results from static and explicit simulations are compared with experimental data and while discrepancies are identified in some of the specimens, the failure mechanism of the proposed topologies can generally be estimated without the need for an empirical investigation. Results suggest that implicit modeling, while more computationally expensive, is as accurate as traditional methods. Additionally, insights into numerical simulations and optimal input parameters are provided to effectively validate structural designs for sandwich-type engineering applications.

This study explores the mechanical performance of triply periodic minimal surface (TPMS) and stochastic lattice structures subjected to low-velocity impact. Two structurally promising geometries—one TPMS-based and one stochastic—were tested and compared with the well-established gyroid. Specimens were fabricated using stereolithography (SLA) and subjected to impact energies of 30 J and 40 J to assess the structural response and energy absorption capabilities. Experimental results show that the proposed TPMS structure exhibits higher impact forces compared with the gyroid, which are associated with significant impactor displacement and deep indentation. These samples demonstrated extensive damage, with cracking propagating through the entire core at higher energies, highlighting their susceptibility to structural failure despite their high initial strength. On the contrary, the stochastic structures allowed localized deformation in the impacted region, thus successfully avoiding catastrophic failure. The impact force efficiency was higher for both gyroid and stochastic geometries, with values ranging between 0.6 and 0.7, indicating effective energy absorption with reduced internal stress gradients. Furthermore, the evaluation of damping performance showed that most structures displayed high damping, as minimal energy was transferred back to the impactor. This work highlights the feasibility and functional versatility of TPMS and stochastic geometries for use in impact mitigation, vibration control, and related engineering applications.

The purpose of the article is to present a point of view on determining the mass moment of inertia coefficient of a tracked vehicle. This coefficient is very useful to be able to estimate the performance of a tracked vehicle, including slips in the converter. Determining vehicle acceleration plays an important role in assessing vehicle mobility. Additionally, during the transition from the Hydroconverter to the hydro-clutch regime, these estimations become quite difficult due to the complexity of the propulsion aggregate (engine and hydrodynamic transmission) and rolling equipment. The algorithm for determining performance is focused on estimating acceleration performance. To validate the proposed model, tests were performed to determine the equivalent reduced moments of inertia at the drive wheel (gravitational method) and the main components (three-wire pendulum method). The dynamic performances determined during the starting process are necessary for the validation of the general model for simulating the longitudinal dynamics of the vehicle. Finally, the differential and algebraic equations of the virtual model approximate more accurately the actual process of the operation of the vehicle. The virtual model, through the data obtained from the simulation process, allows for the determination, indirectly, of the variation of the mass moment of inertia coefficient and its expression of approximation.

Despite the fact that today vehicles are easier to drive and more reliable, the drivers' carefulness is diverted by a large number of factors (road conditions, traffic conditions, phone calls, navigation systems etc.). The automatic system of controlling the windscreen wipers meets exactly one of the carelessness factors. A rain sensor makes the activation of the system of windscreen wipers to become something that you turn on and forget about it. This completely automated system activated by rain measures the rain intensity and also the necessity to turn on the windscreen wipers and with what velocity. Using an advanced optical system, analogue signal processing and a control algorithm, this technology offers more safety and comfort on different weather conditions. The sensor beams an infrared light on the windshield at an angle carefully chosen. If the windshield is dry, the beam is reflected back in the sensor. If on the glass there are rain drops, they will reflect the light in different directions (the wetter the windshield is, the least of the beam ray is reflected back in the sensor).

Triply periodic minimal surface (TPMS) structures raised significant interest in several areas of research due to their unique properties and broad range of applications. The aim of the paper is to verify if such complex metamaterials can be fabricated effectively without defects that could compromise their mechanical response. An implicit modeling approach was used to generate eight novel TPMS structures and one stochastic topology. Multiple specimens were fabricated from a photopolymeric resin using a stereolithography (SLA) technique, and an analysis of the manufactured samples was carried out in terms of surface quality, dimensional and mass deviations, and internal porosity of the material. Laser scanning showed no significant deviations from the designed geometry but highlighted errors during the post-processing stages of manufacturing. Surface analysis resulted in an average roughness of 2.47 µm, a value specific to well-controlled additive manufacturing (AM) techniques. A microscopic examination portrays common types of defects, while an ultrasonic non-destructive inspection method showed no indication of defects in the depth of the samples. Sectioning the samples through water jet cutting exposed interior surfaces with better homogeneity than the exterior ones and the absence of a layer-by-layer aspect. Overall, the samples displayed no major defects and good accuracy, with minor inconsistencies and methods of mitigating them having been presented.