Strength and deformation characteristics of carbon fibre reinforced composite wrapped aluminium foam beams

Sandwich structures fabricated from an aluminium skinned foam enclosed within a carbon fibre reinforced composite structure have the potential application for high-performance on- and off-road automotive vehicles. The deformations and failure of these types of structures are presented, and results indicate that the application of aluminium face sheets with aluminium foam (AF) aids to prevent the delamination of the outer layers of carbon fibre reinforced polymers (CFRP). The load carrying capacity has been increased by utilising a manufacturing method to maintain the adhesion between the core and the skins until the failure stage is reached. The core shear and de-bonded issue associated with this type of sandwich structure can be addressed by this manufacture method. The peak average flexure load capacity of an aluminium foam sandwich structure (AFSS) with a completely wrapped around CFRP skin was 2800 N with a mass of 191 g. This compares favourably with previously used AFSS without the skins, which had a peak average load of 600 N and a mass of 125 g. An initial finite element model for comparison purposes has been developed to represent the structure’s behaviour and predict the associated failure loads. It is proposed that CFRP wrapped around AFSS enhances the structural performance without significant weight gain

Strength and deformation characteristics of carbon fibre reinforced composite wrapped aluminium foam beams

Sandwich structures fabricated from an aluminium skinned foam enclosed within a carbon fibre reinforced composite structure have the potential application for high-performance on- and off-road automotive vehicles. The deformations and failure of these types of structures are presented, and results indicate that the application of aluminium face sheets with aluminium foam (AF) aids to prevent the delamination of the outer layers of carbon fibre reinforced polymers (CFRP). The load carrying capacity has been increased by utilising a manufacturing method to maintain the adhesion between the core and the skins until the failure stage is reached. The core shear and de-bonded issue associated with this type of sandwich structure can be addressed by this manufacture method. The peak average flexure load capacity of an aluminium foam sandwich structure (AFSS) with a completely wrapped around CFRP skin was 2800 N with a mass of 191 g. This compares favourably with previously used AFSS without the skins, which had a peak average load of 600 N and a mass of 125 g. An initial finite element model for comparison purposes has been developed to represent the structure’s behaviour and predict the associated failure loads. It is proposed that CFRP wrapped around AFSS enhances the structural performance without significant weight gain

An intelligent fault diagnosis method using variable weight artificial immune recognizers (V-AIR)

The Artificial Immune Recognition System (AIRS), which has been proved to be a successful classification method in the field of Artificial Immune Systems, has been used in many classification problems and gained good classification effect. However, the network inhibition mechanisms used in these methods are based on the threshold inhibition and the cells with low affinity will be deleted directly from the network, which will misrepresent the key features of the data set for not considering the density information within the data. In this paper, we utilize the concept of data potential field and propose a new weight optimizing network inhibition algorithm called variable weight artificial immune recognizer (V-AIR) where we replace the network inhibiting mechanism based on affinity with the inhibiting mechanism based on weight optimizing. The concept of data potential field was also used to describe the data distribution around training samples and the pattern of a training data belongs to the class with the largest potential field. At last, we used this algorithm to rolling bearing analog fault diagnosis and reciprocating compressor valves fault diagnosis, which get a good classification effect

Emulsion Electrospinning of Polytetrafluoroethylene (PTFE) Nanofibrous Membranes for High-Performance Triboelectric Nanogenerators

Electrospinning is a simple, versatile technique for fabricating fibrous nanomaterials with the desirable features of extremely high porosities and large surface areas. Using emulsion electrospinning, polytetrafluoro­ethylene/polyethene oxide (PTFE/PEO) membranes were fabricated, followed by a sintering process to obtain pure PTFE fibrous membranes, which were further utilized against a polyamide 6 (PA6) membrane for vertical contact-mode triboelectric nanogenerators (TENGs). Electrostatic force microscopy (EFM) measurements of the sintered electrospun PTFE membranes revealed the presence of both positive and negative surface charges owing to the transfer of positive charge from PEO which was further corroborated by FTIR measurements. To enhance the ensuing triboelectric surface charge, a facile negative charge-injection process was carried out onto the electrospun (ES) PTFE subsequently. The fabricated TENG gave a stabilized peak-to-peak open-circuit voltage (<i>V</i>_oc) of up to ∼900 V, a short-circuit current density (<i>J</i>_sc) of ∼20 mA m^–2, and a corresponding charge density of ∼149 μC m^–2, which are ∼12, 14, and 11 times higher than the corresponding values prior to the ion-injection treatment. This increase in the surface charge density is caused by the inversion of positive surface charges with the simultaneous increase in the negative surface charge on the PTFE surface, which was confirmed by using EFM measurements. The negative charge injection led to an enhanced power output density of ∼9 W m^–2 with high stability as confirmed from the continuous operation of the ion-injected PTFE/PA6 TENG for 30 000 operation cycles, without any significant reduction in the output. The work thus introduces a relatively simple, cost-effective, and environmentally friendly technique for fabricating fibrous fluoropolymer polymer membranes with high thermal/chemical resistance in TENG field and a direct ion-injection method which is able to dramatically improve the surface negative charge density of the PTFE fibrous membranes

Expanding the portfolio of tribo-positive materials: aniline formaldehyde condensates for high charge density triboelectric nanogenerators

The rapid uptake of energy harvesting triboelectric nanogenerators (TENGs) for self-powered electronics requires the development of high-performance tribo-materials capable of providing large power outputs. This work reports on the synthesis and use of aniline formaldehyde resin (AFR) for energy-harvesting applications. The facile, acidic-medium reaction between aniline and formaldehyde produces the aniline-formaldehyde condensate, which upon an in-vacuo high temperature curing step provides smooth AFR films with abundant nitrogen and oxygen surface functional groups which can acquire a tribo-positive charge and thus endow AFR with a significantly higher positive tribo-polarity than the existing state-of-art polyamide-6 (PA6). A TENG comprising of optimized thin-layered AFR against a polytetrafluoroethylene (PTFE) film produced a peak-to-peak voltage of up to ~1,000 V, a current density of ~65 mA m⁻², a transferred charge density of ~200 μC m⁻² and an instantaneous power output (energy pulse) of ~11 W m⁻² (28.1 μJ cycle⁻¹), respectively. The suitability of AFR was further supported through the Kelvin probe force microscopy (KPFM) measurements, which reveal a significantly higher average surface potential value of 1.147 V for AFR as compared to 0.87 V for PA6 and a step-by-step increase of the surface potential with the increase of energy generation cycles. The work not only proposes a novel and scalable mouldable AFR synthesis process but also expands with excellent prospects, the current portfolio of tribo-positive materials for triboelectric energy harvesting applications

SHARED MENTAL MODELS AS MODERATORS OF TEAM PROCESS-PERFORMANCE RELATIONSHIPS

The effects of shared mental models on the relationship between episodic team behavioral processes and performance were investigated, while teams were using an expenmentally stimulated construction project planning program. The results indicated that episodic team processes made positive contributions to the team performance. Furthermore, a hierarchical linear regression indicated that the convergence of shared teamwork mental models moderated the effects of team processes on team performance Specifically, the positive Impact of team processes on performance was found to be improved for those teams who shared more similar teamwork mental models than for teams who hold fewer similar teamwork mental models. Potential implications and relevant impacts on future research are discussed