Robustly printable freeform thermal metamaterials

Thermal metamaterials have exhibited great potential on manipulating, controlling and processing the flow of heat, and enabled many promising thermal metadevices, including thermal concentrator, rotator, cloak, etc. However, three long-standing challenges remain formidable, i.e., transformation optics-induced anisotropic material parameters, the limited shape adaptability of experimental thermal metadevices, and a priori knowledge of background temperatures and thermal functionalities. Here, we present robustly printable freeform thermal metamaterials to address these long-standing difficulties. This recipe, taking the local thermal conductivity tensors as the input, resorts to topology optimization for the freeform designs of topological functional cells (TFCs), and then directly assembles and prints them. Three freeform thermal metadevices (concentrator, rotator, and cloak) are specifically designed and 3D-printed, and their omnidirectional concentrating, rotating, and cloaking functionalities are demonstrated both numerically and experimentally. Our study paves a powerful and flexible design paradigm toward advanced thermal metamaterials with complex shapes, omnidirectional functionality, background temperature independence, and fast-prototyping capability.

The design and execution of a laboratory micro hydroelectric power plant

The paper presents a laboratory micro hydroelectric power plant destined to applicative activities. The hydraulic turbine is a Pelton turbine, rebuilt by fast prototyping in Geomagic Design X and printed on a 3 D printer. The turbine casing and the afferent elements are made in-house. The hydrogenator is synchronous being an alternator from a Dacia vehicle. The hydrogenerator load is constituted by 3 groups of light bulbs. We analysed the working of the micro-hydroelectric power plant in idle run and for different loads. As a result of the analysis we found out that it stably works for different loads and by its open construction it is useful for developing students’ ability to understand the phenomena. The installation designed and executed is useful for the engineering students as the pandemic forbids the thematical visits in hydro-energetic facilities.

Preparation of Smart Materials by Additive Manufacturing Technologies: A Review

Over the last few decades, advanced manufacturing and additive printing technologies have made incredible inroads into the fields of engineering, transportation, and healthcare. Among additive manufacturing technologies, 3D printing is gradually emerging as a powerful technique owing to a combination of attractive features, such as fast prototyping, fabrication of complex designs/structures, minimization of waste generation, and easy mass customization. Of late, 4D printing has also been initiated, which is the sophisticated version of the 3D printing. It has an extra advantageous feature: retaining shape memory and being able to provide instructions to the printed parts on how to move or adapt under some environmental conditions, such as, water, wind, light, temperature, or other environmental stimuli. This advanced printing utilizes the response of smart manufactured materials, which offer the capability of changing shapes postproduction over application of any forms of energy. The potential application of 4D printing in the biomedical field is huge. Here, the technology could be applied to tissue engineering, medicine, and configuration of smart biomedical devices. Various characteristics of next generation additive printings, namely 3D and 4D printings, and their use in enhancing the manufacturing domain, their development, and some of the applications have been discussed. Special materials with piezoelectric properties and shape-changing characteristics have also been discussed in comparison with conventional material options for additive printing.

IoT Helper: A Lightweight and Extensible Framework for Fast-Prototyping IoT Architectures

Industry 4.0 is focused on the task of creating Smart Factories, which require the automation of traditional industrial processes and the fully connection and integration of different systems and devices. However, despite the wide availability of tools and technology, developing intelligent applications in the industry framework remains a complex and expensive task. This paper proposes a lightweight, extensible and scalable framework called IoT Helper to facilitate the adoption of IoT and IIoT solutions both in industry and domotics. The framework is designed to be highly flexible and declarative in nature, thus allowing for a wide range of configurations with minimal user efforts. To emphasize the practical applicability or our proposal, we present two real-life use cases where the framework was successfully adopted. We also investigate a crucial aspect of these applications, i.e., what level of scalability can be achieved with a lean generic framework based on inexpensive components such as ours. Comprehensive experimental results show the excellent cost-to-performance ratio of our solution. We consider this to be an important contribution because it paves the way for a more widespread adoption of IIoT-enabling technologies in industry.

3D CAD model reconstruction and fast prototyping of rotational parts: a reverse engineering approach

Purpose This paper aims to present a reverse engineering (RE) approach for three-dimensional (3D) model reconstruction and fast prototyping (FP) of broken chess pieces. Design/methodology/approach A case study involving a broken chess piece was selected to demonstrate the effectiveness of the proposed unconventional RE approach. Initially, a laser 3D scanner was used to acquire a (non-uniform rational B-spline) surface model of the object, which was then processed to develop a parametric computer aided design (CAD) model combined with geometric design and tolerancing (GD&T) technique for evaluation and then for FP of the part using a computer numerical controlled (CNC) machine. Findings The effectiveness of the proposed approach for reconstruction and FP of rotational parts was ascertained through a sample part. The study demonstrates non-contact data acquisition technologies such as 3D laser scanners together with RE systems can support to capture the entire part geometry that was broken/worn and developed quickly through the application of computer aided manufacturing principles and a CNC machine. The results indicate that design communication, customer involvement and FP can be efficiently accomplished by means of an integrated RE workflow combined with rapid product development tools and techniques. Originality/value This research established a RE approach for the acquisition of broken/worn part data and the development of parametric CAD models. Then, the developed 3D CAD model was inspected for accuracy by means of the GD&T approach and rapidly developed using a CNC machine. Further, the proposed RE led FP approach can provide solutions to similar industrial situations wherein agility in the product design and development process is necessary to produce physical samples and functional replacement parts for aging systems in a short turnaround time.

Optimization of a Handwriting Method by an Automated Ink Pen for Cost-Effective and Sustainable Sensors

In this work, we present a do-it-yourself (DIY) approach for the environmental-friendly fabrication of printed electronic devices and sensors. The setup consists only of an automated handwriting robot and pens filled with silver conductive inks. Here, we thoroughly studied the fabrication technique and different optimized parameters. The best-achieved results were 300 mΩ/sq as sheet resistance with a printing resolution of 200 µm. The optimized parameters were used to manufacture fully functional electronics devices: a capacitive sensor and a RFID tag, essential for the remote reading of the measurements. This technique for printed electronics represents an alternative for fast-prototyping and ultra-low-cost fabrication because of both the cheap equipment required and the minimal waste of materials, which is especially interesting for the development of cost-effective sensors.