Materials selection tools in professional appliances: hypothesis to estimate materials’ performance and impact on industrial processes

Concept The use of materials’ selection in professional appliances increased in recent times, thanks to its potential pre-evaluation of materials’ performance and impact on industrial production processes. Through a collaboration among Politecnico di Milano (Department of Design and Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”) and Electrolux Professional S.p.A. (Global Research & Development, Innovation & Technologies Area), an evaluation of materials’ tangible and intangible properties has been developed using non-traditional methods. Among all the currently professional appliances, the oven environment has been chosen as the most emblematic study case. In the first part, this work evidences the major limits and critical points of the materials’ selection tools currently and most commonly proposed in industrial applications. Within these, the main key points highlighted are the translation and connection of quantitative and qualitative properties and the risk associated to the materials selection process reliability. In a second step, some ameliorative hypotheses are built to overcome these limits, using a repeatable and suitable method for different materials selection cases. Motivations and Objectives The research aim is to develop an innovative and versatile method for the materials selection in professional appliances field, used by engineers and designers. From the Ashby [1] and the Karana [2] selection strategies, the non-traditional materials selection methodology would offer a complete evaluation of materials’ tangible and intangible properties. Different variables, indeed, have been taken into consideration: material’s technical properties (e.g. mechanical, thermal and processability parameters), durability (e.g. food chemicals and detergents), food-material compliance and customer perception of properties. The need of a unique materials selection method, able to convert quantitative to qualitative evaluation of properties and to estimate the risk associated to the materials selection reliability, driven the research. A procedure, which evaluates components’ life and possible failure modes (based on DOE and FMEA) [3] [4] [5], is under development in order to integrate these information into the future products development. Results and Discussion The research presents the development of the materials selection methodology under consideration supported by some case studies that focus on durability properties of materials

Auditory and tactile recognition of resonant material vibrations in a passive task of bouncing perception

Besides vision and audition, everyday materials can be passively explored also using touch if they provide tactile feedback to users, for instance in consequence of an external force exciting their natural resonances. If such resonances are known to provide informative auditory cues of material, on the other hand their role when a recognition is made through touch is debatable. Even more questionable is a material recognition from their reproductions: if happening, then they could be used to enrich existing touch-screen interactions with ecological auditory and haptic feedback furthermore requiring inexpensive actuation. With this goal in mind, two experiments are proposed evaluating user\u2019s ability to classify wooden, plastic, and metallic surfaces respectively using auditory and haptic cues. Al- though the literature reports successful auditory classification of everyday material simulations, especially the passive recognition of such material reproductions by holding a finger on a vibrating glass surface has never been tested. By separately reproducing the sound and vibration of a ping-pong ball bouncing on wood, plastic and metal surfaces, our tests report not only auditory, but also tac- tile recognition of the same materials significantly above chance. Discrepancies existing between our and previously reported results are discussed

A control system for preventing cavitation of centrifugal pumps

Cavitation is a well-known phenomenon that may occur, among other turbo-machines, in centrifugal pumps and can result in severe damage of both the pump and the whole hydraulic system. There are situations in which, in principle, the cavitation could be avoided by detecting the condition of incipient cavitation, and changing slightly the working point of the whole system in order to move away from that condition. In the present paper two simple closed-loop control strategies are implemented, acting on the pump's rotational speed and fed by the measurements of a set of inertial sensors. In particular, the research is focused on a centrifugal pump normally employed in hydraulic systems. The pump operates in a dedicated test rig, where cavitation can be induced by acting on a reservoir's pressure. Three accelerometers are installed in the pump body along three orthogonal axes. An extensive set of experiments has been carried out at different flow rates and a number of signals' features both in the time domain and in the frequency domain have been considered as indicators of incipient cavitation. The amount of energy of the signal captured by the accelerometer in the component orthogonal to the flow direction, in the band from 10 to 12.8 kHz, demonstrated to be effective in detecting the incipient cavitation, by selecting a proper (condition-dependent) threshold. Therefore, two simple controllers have been designed: the first regulates the speed of the pump, to recover from cavitation, bringing the indicator back to the nominal value, while the second allows to reduce the pump's rotational speed when the cavitation detector indicates the incipient cavitation and restoring the nominal speed when possible. The latter approach is rather general, because the threshold-based detector can be substituted by any detector providing binary output. Experimental results are reported that demonstrate the effectiveness of the approach

A reliable and computationally efficient model for professional gas boilers

Gas boilers can be integrated into professional ovens for steamcooking processes. Their heat-transfer efficiency depends on several parameters, as exhaust gas temperature, combustion stability, fuel type, excess air. Computational fluid dynamics (CFD henceforth) provides a viable option to assess several digital prototypes of gas boilers under different operation conditions. Short setup-time, low computational cost and close matching with experimental results are key features of a CFD model suitable for the industrial design. We propose a reliable and computationally-efficient CFD model for gas boilers, operating under steady conditions. The model does not take explicitly into account both combustion and water boiling. The accuracy of the proposed model is confirmed by the excellent agreement between experimental measurements of the exhaust gas temperatures and the corresponding numerical results

Study of chemical environments for washing and descaling of food processing appliances: An insight in commercial cleaning products

Food processing appliances are constantly exposed to harsh environments, resulting from a mix of chemical, thermal, and mechanical stresses. Considering cleaning processes, which are needed to preserve their safety and performances, exposes them to a wide spectrum of chemical products. Aim of this work is a comprehensive analysis of the current commercial cleaning products, identifying the differences among functional classes and the characteristics of washing environments. Data here summarized can be useful both to increase the knowledge about industrial washing environments and to enhance materials selection processes effectiveness, which should take into account materials durability towards complex chemical mixtures

Ellagic Acid and Polyhydroxylated Urolithins Are Potent Catalytic Inhibitors of Human Topoisomerase II: An in Vitro Study

Ellagic acid (EA), a natural polyphenol abundant in fruits and common in our diet, is under intense investigation for its chemopreventive activity resulting from multiple effects. EA inhibits topoisomerase II, but the effects on the human enzyme of urolithins, its monolactone metabolites, are not known. Therefore, the action of several synthetic urolithins toward topoisomerases II was evaluated, showing that polyhydroxylated urolithins, EA, and EA-related compounds are potent inhibitors of the \u3b1 and \u3b2 isoforms of human topoisomerase II at submicromolar concentrations. Competition tests demonstrate a dose-dependent relationship between ATP and the inhibition of the enzyme. Docking experiments show that the active compounds bind the ATP pocket of the human enzyme, thus supporting the hypothesis that EA and polyhydroxylated urolithins act as ATP-competitive inhibitors of human topoisomerase II

Effect of food chemicals and temperature on mechanical reliability of bio-based glass fibers reinforced polyamide

This paper presents an experimental study to assess the effects of food chemicals and temperature on the mechanical performance of glass fiber reinforced bio-based polyamide. The diffusion of food chemicals was mainly driven by thermal energy, following Arrhenius law in all tested environments. Degradation of mechanical properties and decrease in reliability were assessed, due to the plasticization of polymer matrix. Secondary but not negligible effect on flexural strength degradation is given by the different chemical interaction between polymeric chains and molecules of food chemicals. Colour change was measured and resulted to be positively correlated to diffusion