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The purpose of this study is to investigate the efficiency of applied vibration in improving the forming quality (mechanical property and dynamics characteristics) of fused filament fabrication (FFF) parts.

A vibrating FFF three-dimensional printer was set up, with which the samples fabricated in different directions were manufactured separately without and with vibration applied. A series of experimental tests, including tensile tests, dynamics tests and scanning electron microscopy (SEM) tests, were performed on these samples to experimentally quantify the effect of applied vibration on their forming quality.

It has been found that the applied vibration can significantly increase the tensile strength and plasticity of the samples built in Z-direction, and obviously decrease the orthogonal anisotropy. It can also significantly change the sample’s natural frequency, decrease the resonant response and increase the modal damping ratio, thus improve the anti-vibration capability of FFF samples. In addition, the SEM analysis confirmed that applying vibration into FFF process could improve the forming quality of the fabricated part.

Future research may be focused on investigating the efficiency of applied vibration in improving the forming quality of parts fabricated by the other additive manufacturing techniques.

This study helps to improve the reliability of FFF parts and extend the application range of FFF technology.

A novel method to improve the forming quality of FFF parts is provided and the available information about the performance of dynamics characteristics.

The purpose of this paper is to check the efficiency of isogeometric analysis (IGA) by comparing its results with classical finite element method (FEM), generalized finite element method (GFEM) and other enriched versions of FEM through numerical examples of free vibration problems.

Since its conception, IGA was widely applied in several problems. In this paper, IGA is applied for free vibration of elastic rods, beams and trusses. The results are compared with FEM, GFEM and the enriched methods, concerning frequency spectra and convergence rates.

The results show advantages of IGA over FEM and GFEM in the frequency error spectra, mostly in the higher frequencies.

Isogeometric analysis shows a feasible tool in structural analysis, with emphasis for problems that requires a high amount of vibration modes.

UPON completion of the design for the engine mounting it is most desirable that some ground testing should be carried out before the mounting is flight tested. These tests will provide information on the mounting resonances and modes of vibration, deflexions of the engine and mounting under load and they may also be extended to include proof and ultimate load tests for various critical flight cases. The degree of vibration isolation achieved can also be estimated bearing in mind the differences in suspension on the test beds compared with the actual aeroplane and any changes found to be necessary can be incorporated and tested more readily on the ground than in the air.

Early aircraft engines were usually bolted direct to the aircraft structure and no attempt was made to prevent the vibrations which they set up from being transmitted to the airframe. With increasing engine powers and the use of larger airscrews these vibrations eventually become of sufficient magnitude in some cases to cause annoyance to the occupants of the aircraft and also failure by fatigue of parts of the structure. Various attempts were made both to analyse the source of the vibrations with a view to eliminating them or reducing them to an acceptable magnitude. Where this was not possible attempts were made to isolate the disturbances from the airframe and its occupants. This paper presents the basic theory of vibration isolation and gives an account of the various sources of vibration met with in reciprocating, turbo‐propeller and pure‐jet installations. The loads acting on the engine during various conditions of flight are then examined as a knowledge of these is required in order to determine the strength of the supporting units. Various practical engine mounting configurations are then considered which will give vibration isolation together with adequate support of the engine under all conditions of flight. Some account is given of the properties of rubber and the design and testing of rubber vibration isolators, and some installation problems are examined. Finally, the complete programme of testing an installation both on the test‐bed and inflight to evaluate the degree of vibration isolation achieved is described, together with various criteria of acceptability both from a structural and physiological standpoint. A bibliography covering the various sections is included.

This paper aims to deal with heat transfer enhancement because of transverse vibration on counter flow concentric pipe heat exchanger. Experiments were performed at different vibrator positions with varying amplitudes and frequencies.

Tests are carried out at 4 different vibration frequencies (20, 40, 60 and 100 Hz), 3 vibration amplitudes (23, 46 and 69 mm) and at 3 vibrator positions (1/4, 1/2 and 3/4 of pipe length) with respect to hot water inlet under turbulent flow condition.

Experimental results indicate that Nusselt number is enhanced to a maximum extent of 44% with vibration when compared to Nusselt number without vibration at a frequency of 40 Hz, an amplitude of 69 mm and at a vibrator position of one-fourth of pipe length with respect to hot water inlet.

Empirical correlation is developed from experimental data to estimate the heat transfer coefficient with vibration for experimental frequency range with an error estimate of approximately ±10%.

The purpose of this study is to explore the importance of vibrations during welding process. In recent years, welding has gained its supremacy in the field of production. The main set back of the welding process is induced residual stresses, which is a major cause for many welding defects. These defects can be minimized by post-weld heat treatment methods, which is a time consuming and laborious process. In the recent past, a technique of exciting the weld-pool by vibrating the work-pieces was also adopted to minimize the above-mentioned stresses. A novel technique of electrode vibration is another effective way of transferring the vibrations to the weld-pool to influence the induced residual stress.

In this research, the electrode is vibrated with the help of an electric motor. The specimens were prepared as per American Society for Testing and Materials standards and welded with varying frequencies and voltages. The weldments are tested for hardness along the weld bead and heat affected zone, also the microstructure of the fusion zone is analyzed.

It is observed that there is an improvement in the hardness because of the grain refinement, which is a result of proper excitation of the weld-pool. It is observed that there is an improvement in hardness test up to 28.69% when compared with the conventional welding process. The peak value of hardness is observed at a frequency of 4,450 Hz. This is because of fine grain structure at this frequency, which is observed through the microstructure analysis.

A novel technique is introduced to refine the weld-pool through electrode vibrations. To improve the hardness of the welded joints, vibrations play a major role by refining the grain structure. The vibrations are imparted with the help of a special equipment attached to the electrode.

The purpose of this paper is to identify if the implementation of ultrasonic vibration in laser engineered net shaping (LENS) process can help to reduce internal weaknesses such as porosity, coarse primary TiB whisker and heterogeneous distribution of TiB reinforcement in the LENS-fabricated TiB reinforced Ti matrix composites (TiB-TMC) parts.

An experimental investigation is performed to achieve the results for comparative studies under different fabrication conditions through quantitative data analysis. An approach of microstructural characterization and mechanical testing is conducted to obtain the output attributes. In addition, the theoretical analysis of the physics of ultrasonic vibration in the melting materials is presented to explain the influences of ultrasonic vibration on the microstructural evolution occurred in the part fabrication.

Because of the nonlinear effects of acoustic streaming and cavitation induced by ultrasonic vibration, porosity is significantly reduced and a relatively small variation of pore sizes is achieved. Ultrasonic vibration also causes the formation of smaller TiB whiskers that distribute along grain boundaries with a homogeneous dispersion. Additionally, a quasi-continuous network (QCN) microstructure is considerably finer than that produced by LENS process without ultrasonic vibration. The refinements of both reinforcing TiB whiskers and QCN microstructural grains further improve the microhardness of TiB-TMC parts.

The novel ultrasonic vibration-assisted (UV-A) LENS process of TiB-TMC is conducted in this work for the first time to improve the process performance and part quality.

The purpose of this paper is to investigate the optimum design of a quarter car passive suspension system using a particle swarm optimization algorithm in order to minimize the applied loads and vibrations.

The road excitation is assumed as zero-mean random field and modeled by single-sided power spectral density (PSD) based on international standard ISO 8608. The variance of sprung mass displacements and variance of dynamic applied load are evaluated by PSD functions and used as cost function for the optimization.

The advantages in using this methodology are emphasized by an example of the multi-objective optimization design of suspension parameters and the results are compared with values reported in the literature and other gradient based and heuristic algorithms. The paper shows that the algorithm effectively leads to reliable results for suspension parameters with low computational effort.

The procedure is applied to a quarter car passive suspension design.

The proposed procedure implies substantial time savings due to frequency domain analysis.

The paper proposes a procedure that allows complex optimization designs to be feasible and cost effective.

The design optimization is performed in the frequency domain taking into account standard defined road profiles PSD without the need to simulate in the time domain.

Fretting corrosion—a surface damage occurring between two closely fitting surfaces subject to slight vibrational movement—has caused trouble in machinery ever since the first closely fitting machined parts were put together. It is something different from ordinary wear or rusting of the usual chemical nature, and it is not always recognised as fretting corrosion by users of equipment in which it occurs. ‘Friction oxidation,’ ‘wear oxidation,’ ‘false brinelling,’ ‘chafing,’ ‘bleeding’ and ‘cocoa’ are some of the names that have been applied to the phenomenon. One of the results of work carried out by the Mechanical Engineering Research Laboratory of the D.S.I.R., briefly described in CORROSION TECHNOLOGY, May 1954, is that it is possible to correlate the degree of damage with such variables as total number of oscillations, load or atmospheric humidity. In the United States, too, much work has been done on fretting corrosion and ways of combating it. So that as many as possible could benefit from this research, the American Society for Testing Materials organised a Symposium in which leading experts gave their findings. The Symposium has recently been published as a booklet. Here are shortened versions of two of the papers presented.

The Presidential Address to the Liverpool Engineering Society by Mr. Farthing (the salient points of which are reproduced in this issue) has particular bearing upon lubrication and especially on young lubrication engineers. Mr. Farthing stressed the very wide field open to young engineers and the difficulties associated with training in order to cover as wide a field as may be necessary. It is usually so important to gain a wide knowledge before one can specialise and this is certainly the case with lubrication engineers. One cannot begin to fully appreciate the intricacies of a lubrication system with all its accessory components lubricating and guarding, for example, a large motive power plant or rolling mill, until one has more than a mere working knowledge of the plant itself, the duties it must perform, how it performs them and the snags that arise which might be overcome by correct lubrication. In view of the fact that lubrication systems are just as important in a textile mill as in a power station or a large brick works, the almost impossible‐to‐achieve‐range of knowledge that would simplify the work of a lubrication engineer is very obvious. Fortunately, lubricating principles apply to most cases and knowing how to apply one's knowledge from basic principles is the key to success in this difficult profession.