Roberto Palazzetti

Influence of electrospun nanofibers on the interlaminar properties of unidirectional epoxy resin/glass fiber composite laminates

Nylon 6,6 nanofibers were interleaved in the mid-plane of glass fiber/epoxy matrix composite laminates for Mode I and II fracture mechanic tests. The present study investigates the effect of the nanofibers on the laminates’ mechanical response. Results showed that Nylon 6,6 nanofibers improved specimen’s fracture mechanic behavior: the initial energy release rates GIC and GIIC increased 62% and 109%, respectively, when nanofibrous interlayer was used. Scanning electron microscope micrographs showed that nanofiber bridging mechanism enhances performances of the nanomodified specimens, still able to link the layers when the matrix is broken.

Flexural behavior of carbon and glass fiber composite laminates reinforced with Nylon 6,6 electrospun nanofibers

Nylon 6,6 nanofibers manufactured by means of electrospinning have been used to interleave Mode II fracture mechanics glass and carbon unidirectional fiber composite specimens. The aim of this work was to study the effect of the nanofibers materials in their ability to reinforce the interleave. Experimental testing was carried out on specimens with a nanofibrous mat interleaved into a delaminated interface. Specimens of 10, 16 and 18 layers were manufactured and tested. Results demonstrated that the effect of nanofibers was different between the two materials and that the fiber materials play an important role in the reinforcement mechanism of the nanofibers.

Delamination assessment in structures made of composites based on general signal correlation

This paper considers a vibration-based damage assessment approach which is based on the general idea for signal cross-correlation. Here the method is demonstrated and validated on a composite laminate beam and it is applied for the purposes of delamination assessment in composite structures. The method uses two measures of cross-correlation between two vibration signals measured in different points on the structure in order to diagnose the delamination. The linear cross-correlation as well as a new measure for nonlinear cross-correlation, the mutual information, are introduced and applied for the purposes of delamination assessment. The delamination assessment is based on the comparison of the measures for the healthy and the damaged state of the structure. In this study, the method is applied using the free decay responses of the beam. Two delamination indices are introduced and they are used for the purposes of delamination detection and localization.

Integrated Mechanical, Thermal, Data, and Power Transfer Interfaces for Future Space Robotics

In-situ connectability among modules of a space system can provide significantly enhanced flexibility, adaptability, and robustness for space exploration and servicing missions. Connection of modules in extra-terrestrial environment is hence a topic of rising importance in modern orbital or planetary missions. As an example, the increasing number of satellites sent to space have introduced a large set of connections of various type, for transferring mechanical loads, data, electrical power and heat from one module to another. This paper provides a comprehensive review of published work in space robotic connections and presents the different transfer types developed and used to date in robotic applications for orbital and extra-terrestrial planetary missions. The aims of this paper are to present a detailed analysis of the state of the art available technologies, to make an analysis of and comparison among different solutions to common problems, to synthesize and identify future connectability research, and to lay the foundation for future European space robotic connectability effort and work for a complex and growing important future space missions. All types are described in their base characteristics and evaluated for orbital and planetary environments. This analysis shows that despite the large number of connectors developed for each of the four functionalities (mechanical, thermal, data, and electrical power) here considered, the trend is that researchers are integrating more than one functionalizes into a single equipment or device, to reduce costs and improve standardization. The outcomes of this literature review have contributed toward the design of a future multifunctional, standard and scalable interface at the early stage of the Standard Interface for Robotic Manipulation of Payloads in Future Space Missions (SIROM) project, a European Commission funded Horizon 2020 project. SIROM interfaces will be employed by European prime contractors in future extra-terrestrial missions.

Study on lubrication effect on motorbike chain transmissions

Purpose This paper reports on the findings of first of its kind to examine motorbike’s chain transmission, focusing on chain lubrication and its effect on the temperature, efficiency and vibrations of the transmission. The novelty of the paper is to investigate holistically the lubrication effect on the transmission by comparing its dynamic performances under three different lubrication conditions: chain not lubricated at all, chain lubricated with a spray polytetrafluoroethylene (PTFE) addicted lube and chain lubricated with a mineral oil at every minute of the test. Design/methodology/approach A novel mechatronic test rig has been designed and manufactured using a thermocamera, a dynamometer and an accelerometer respectively. The rig enables a multi-parameter dynamic and real-time sensing investigation of any motorbike chain system by recording temperature, transmissions efficiency and vibrations for any tests by. An experimental investigation has been conducted by running a chain under three aforementioned lube conditions at different speeds with the purposes of: (A) measuring the effect that each lube condition has on three critical parameters: temperature, vibrations and the efficiency of the transmission, and (B) identify the best conditions for practical use. Findings Results showed that proper use of lubricant can increase the efficiency of the system, by an estimated average of 4.1% is desirable. Additionally, using a continuous lubrication with a mineral oil lubricant leads to better transmission compared to the use of the spray PTFE from the efficiency and thermal points of view. Originality/value This work presents an experimental investigation on the effect of two different kinds of lubrication form motorbike chain on transmission’s efficiency. The findings are still valid for different applications of chain transmission in dirty environments. Novelty of the paper is highlighted as follows: this is the first work scientifically investigating the importance of lubrication on chain in harsh environments, particularly of motorbike chain. The work reports a comprehensive lete set experiments and analysis of thermal and mechanical effect because of the presence of lubricant has never been shown. Three kinds of lubricants have been used, and show their distinctive effects which are separately highlighted.