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The purpose of this paper is to investigate the use of embedded Shape Memory Alloy (SMA) nitinol wire for the enhancement of vibration and damping characteristics of filament-wound fiber-reinforced plastic composite hollow shafts.

The plain Glass Fiber-Reinforced Plastic (GFRP) and plain Carbon Fiber-Reinforced Plastic (CFRP) hollow shafts were manufactured by filament winding technique. Experimental modal analysis was conducted for plain hollow shafts of C1045 steel, GFRP and CFRP by subjecting them to flexural vibrations as per ASTM standard C747, with both ends clamped (C-C) end condition to investigate their vibration and damping behavior in terms of first natural frequency, damping time and damping ratio. Nitinol wires pre-stressed at various pre-strains (2, 4 and 6 per cent) were embedded with CFRP hollow shafts following same manufacturing technique, and similar experimental modal analysis was carried out by activating nitinol wires. The first natural frequencies of all the shaft materials were also predicted theoretically and compared with experimental measurements.

Among the three materials C1045 steel, plain GFRP and plain CFRP, the vibration and damping behavior were found to be the best for plain CFRP. Hence, CFRP shafts were considered for further improvement by embedding nitinol wires at pre-stressed condition. For CFRP shafts embedded with nitinol wires, the damping time decreased; and damping ratio and first natural frequency increased with increase in percentage of pre-strain. In comparison with plain CFRP, 7 per cent increase in first natural frequency and 100 per cent increase in damping ratio were observed for nitinol embedded CFRP shafts with 6 per cent pre-strain. Theoretical predictions of the first natural frequencies agree well with the experimental results for all the shaft materials.

The effect of nitinol on vibration and damping characteristics of filament wound hollow CFRP composite shafts with different pre-strains has not been studied extensively by the previous researchers. This paper addresses the effect of embedded nitinol wires pre-stressed at three varied pre-strains, that is, 2, 4 and 6 per cent on the vibration and damping characteristics of composite hollow CFRP shafts manufactured by filament winding technique.

The synergistic effect of functionalization of multi-walled carbon nanotubes (CNT) using KMnO4 oxidation and initial tensile deformation on the electrical resistance of nanotube network/polyurethane composite subjected to elongation was studied.

Though the initial deformation irreversibly changed the arrangement of carbon nanotube network, subsequent cyclic elongation confirmed stable resistance values. The increased strain-dependent resistance of stimulated nanotube network/polyurethane composite was demonstrated by monitoring vibration of tambour leather after a bead impact and finger flexion.

The results showed a tenfold composite resistance increase for the composite prepared from KMnO₄ oxidized nanotubes, quantified by a so-called gauge factor, from a value of about 20 in comparison to the network prepared from pristine nanotubes. This is a substantial increase, which ranks the stimulated composite among materials with the highest electromechanical response.

The results in this paper are new and have not been published yet. The paper combines different ideas which are developed together. It presents a new concept of synergistic effect of CNT oxidation and application of pre-strain simulation. Oxidation and pre-strain increases by several times the sensitivity of the tested composites which are predetermined for use as strain sensors of various sizes and shapes.

To understand the roles of service‐related parameters, such as imposed cyclic strain amplitude and cyclic strain rate, on the stress relaxation behaviour of eutectic Sn‐Ag solder joints.

Cyclic shear straining with associated stress relaxation at the shear strain extremes imposed was carried out on pre‐strained eutectic Sn‐Ag solder joints with various cyclic shear straining conditions. Results from such experiments were compared with previously reported findings from monotonic shear straining and stress relaxation tests.

At higher testing temperatures with a larger cyclic strain amplitude, stress states realized at the subsequent cycle are comparable with, or even gradually increase on, those experienced at the previous cycle, especially after few cycles. The maximum shear stress obtained at each cycle and residual stress during stress relaxation are strongly affected by cyclic strain rate. Stress relaxation during subsequent cycles of straining was found to be strongly dependent on the test temperature, and the imposed cyclic strain amplitude and cyclic strain rate.

In this paper, the experiments were carried out on eutectic Sn‐Ag solder joints with about a 100 μm joint thickness, which are, therefore, representative of those used in microelectronics. Also, there is no systematic study reporting the effects of cyclic straining conditions on the stress relaxation behaviour of eutectic Sn‐Ag solder for this joint configuration in the published literature.

The purpose of this paper is to analyze theoretically the influence of normal stress on the formability of aluminum alloy sheets in non-linear strain paths.

Four loading modes of non-linear strain paths are investigated in detail to consider the effect of normal stress on formability of aluminum alloy sheets.

Results show that the influence of normal stress in the first stage can be ignored. However, the normal stress in the second stage enhances the formability of aluminum alloy sheets obviously. Besides, the normal stress in the second stage is found to have larger effect on forming limit stress than that in the first stage.

Maybe more experiment data should be obtained to support the theoretical findings.

This current study provides a better understanding of normal stress effect on the formability of aluminum alloy sheets in non-linear strain paths. Since the reacting stage of normal stress play important roles in normal stress effect on the formability of aluminum alloy sheets, the insight obtained in this paper will help to judge the instability of aluminum alloy sheets in complex forming processes with normal stress reacting on the sheet or tube.

PEN fibres are well known for their high performance properties, resistance, and good tensile properties. Their potential markets are the packaging, film and fibre markets. For tyre yarns in particular, the response to dynamic deformations at elevated temperatures is interesting. The ultimate modulus of PEN fibres is substantially higher than that of polethylenetrephtalate (PET). However, in the amorphous domains of PEN, the rotation of the naphthalene rings induces conformational transitions, which negatively influence the dynamic mechanical properties (Militký, 1999)

The main aim of this contribution is to measure and characterize the dynamic mechanical spectra of PEN fibres. These spectra are obtained at various levels of pre-straining. The analysis is based on the real part of the dynamic modulus and on an evaluation of the loss tangent. The simple model of dynamic behaviour based on the standard linear viscoelastic body is presented. The special apparatus for measuring dynamic behaviour under various types of deformation (tension, compression, bending, shearing) is described in detail.

The development of a 3D printing method for the textile hybrid structure that can both be a solution to the conventional drawbacks of 3D printing method and a step forward to a garment making industry.

A novel 3D printing method using the textile hybrid structure was developed to generate 3D object without support structures.

3D printing of curved panels without support structure was possible by using fabric tension and residual stress.

Garment panels can be 3D printed without support structures by utilizing the idea of textile hybrid structure. Garment panels are expected to be modelled and printed easily using the Garment Panel Printer (GPP) software developed in this study.

3D printing method developed in the study is expected to reduce the time and material previously needed for support structures.

Comprehensive preparatory experiments were made to determine the design parameters. Various experiments were designed to test the feasibility and validity of proposed method.

The purpose of this paper is to study the buckling and the vibration of the beam induced by atom/molecule adsorption using the nonlocal Euler‐Bernoulli beam model with initial axial stress.

The nonlocal parameter associated with adsorbed mass and bending rigidity variations of the beam induced by adsorbates are taken into account, and the buckling and dynamic behaviors are obtained via the Hamilton's principle, in which the potential energy between adsorbates and surfaces of the beam, the bending energy, the external work and the kinetic energy are summed as the Lagrangian function.

The results show that, for both buckling and resonant frequency, the nonlocal effect should be considered when the beam scales down to several hundreds of nanometres, especially for higher mode numbers.

The present paper gives the exact expressions for the buckling and resonant frequency of a simple‐supported nonlocal beam with initial axial stress. Different from previous works, the mass increasing and bending rigidity of the beam are found size‐dependent (nonlocal effect), resulting in possible different static and dynamic behaviors of the beam when atom/molecular adsorption occurs. The exact expressions obtained for the buckling and resonant frequency may be helpful to the design and application of micro‐ and nanobeam‐based sensors/resonators.

GREAT progress has been made in recent years in both fields of aircraft design and manufacture. No longer is the designer completely in the dark regarding the operational loads his aircraft will have to sustain, nor completely ignorant of the capabilities of its structure. Progress has brought knowledge of the sort of operational load likely to be encountered in both flight and landing operations as well as powerful methods of analysis of aircraft structures. Even that, however, is not enough, for without a thorough understanding of the possibilities and properties of the materials at the designer's command, he cannot hope to utilize such knowledge to the full.

The purpose of this paper is the microstructural and mechanical characterization of a biomedical Ti‐6Al‐4V alloy produced by electron beam melting, and the study of the stability of the as‐built microstructure upon heat treatment.

Ti‐6Al‐4V alloy produced by electron beam melting has been mechanically characterized through tensile and fatigue testing. Its microstructure has been investigated by optical observation after etching and by X‐ray diffractometry analysis. The stability of the microstructure of the as‐built material has been deepened carrying out suitable heat treatments, after an analysis by dilatometry test.

The microstructure of a Ti‐6Al‐4V alloy produced by electron beam melting has a very fine and acicular morphology, because of the intrinsically high‐solidification rate of the process. This microstructure is very stable, and the traditional thermal treatments cannot modify it; the microstructure changes significantly only when an amount of strain is introduced in the material. However, the mechanical properties of the alloy produced by electron beam melting are good.

The paper provides evidence of the microstructural stability of the material produced by electron beam melting. Even if the microstructure of the as‐built material is not recommended by the specific ISO standard, the related mechanical properties are fully satisfactory. This is a significant indication from the point of view of the production of Ti‐6Al‐4V orthopaedic and dental prostheses by electron beam melting.

This study aims to develop an innovative actuator for improving the performance of future aircraft, by adapting the airfoil shape according to the flight conditions. The flap’s camber of a civil regional transportation aircraft’s trailing edge actuated and morphed with the use of shape memory alloys (SMA) actuator technology, instead of the conventional split flap mechanism is studied.

For the flap’s members sizing an efficient methodology is utilised based on finite element (FE) stress analysis combined to analytically formulated design criteria. A mechanical simulation within an FE approach simulated the performance of the moving rib, integrating both aerodynamic loads and SMA phenomenology, implementing Lagouda’s constitutive model. Aim of this numerical simulation is to provide guidelines for further development of the flap. A three-dimensional assembly of the flap is constructed to produce manufacturing drawing and to ensure that during its morphing no interference between the members occurrs. Eventually, the manufactured flap is integrated on a test rig and the experimental characterisations under no and static loads, and dynamic excitation are performed.

Experimental results showed that the rib’s SMA mechanism can adequate function under load providing satisfactory morphing capabilities.

The investigated approach is an internal into the flap mechanism based on the shape memory effect of thin wires. In the developed mechanism, SMA wires are attached to the wing structure, where they function as actuating elements.