Distortion of a twisted beam passing through a plasma layer

This work presents an investigation on the free vibration behavior of rotating pre-twisted functionally graded graphene platelets reinforced composite (FG-GPLRC) laminated blades/beams with an attached point mass. The considered beams are constituted of [Formula: see text] layers which are bonded perfectly and made of a mixture of isotropic polymer matrix and graphene platelets (GPLs). The weight fraction of GPLs changes in a layer-wise manner. The effective material properties of FG-GPLRC layers are computed by using the modified Halpin-Tsai model together with rule of mixture. The free vibration eigenvalue equations are developed based on the Reddy’s third-order shear deformation theory (TSDT) using the Chebyshev–Ritz method under different boundary conditions. After validating the approach, the influences of the GPLs distribution pattern, GPLs weight fraction, angular velocity, the variation of the angle of twist along the beam axis, the ratio of attached mass to the beam mass, boundary conditions, position of attached mass, and geometry on the vibration behavior are investigated. The findings demonstrate that the natural frequencies of the rotating pre-twisted FG-GPLRC laminated beams significantly increases by adding a very small amount of GPLs into polymer matrix. It is shown that placing more GPLs near the top and bottom surfaces of the pre-twisted beam is an effective way to strengthen the pre-twisted beam stiffness and increase the natural frequencies.

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Dynamic characteristics of a drill in the drilling process

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/095440503321148803 ◽

2003 ◽

Vol 217 (2) ◽

pp. 161-167 ◽

Cited By ~ 10

Author(s):

B W Huang

Keyword(s):

Dynamic Characteristics ◽

High Speed ◽

Thrust Force ◽

Time Dependent ◽

Drilling Process ◽

Improve Quality ◽

Vibration Model ◽

High Speed Drilling ◽

Spinning Speed ◽

Twisted Beam

The dynamic characteristics of high-speed drilling were investigated in this study. To improve quality and produce a higher production rate, the dynamic characteristics of the drilling process need to be studied. A pre-twisted beam is used to simulate the drill. The moving Winkler-type elastic foundation is used to approximate the drilling process. A time-dependent vibration model for drilling is presented. The spinning speed, pre-twisted angle and thrust force effects of the drill are considered. The numerical analysis indicates that the natural frequency is suddenly reduced as the drill moves into a workpiece.

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Surface Immobilization of Synthetic Proteins Via Plasma Polymer Interlayers

MRS Proceedings ◽

10.1557/proc-544-9 ◽

1998 ◽

Vol 544 ◽

Cited By ~ 6

Author(s):

Hans J Griesser ◽

Keith M McLean ◽

Gerrit J Beumer ◽

Xiaoyi Gong ◽

Peter Kingshot ◽

...

Keyword(s):

Carboxylic Acid ◽

Cell Attachment ◽

Plasma Layer ◽

Polymeric Materials ◽

Covalent Immobilization ◽

Biologically Active ◽

Plasma Polymer ◽

Rf Plasma ◽

Bulk Materials ◽

Synthetic Proteins

AbstractCoatings of biologically active molecules on synthetic ”bulk“materials are of much interest for biomedical applications since they can in principle elicit specific, predictable. controlled responses of the host environment to an implanted device. However, issues such as shelf life. storage conditions, biological safety, and enzymatic attack in the biological environment must be considered; synthetic proteins may offer advantages. In this study we investigated the covalent immobilization onto polymeric materials of synthetic proteins which possess some properties that mimic those of the natural protein collagen, particularly the ability to form triple helical structures, and thus may provide similar bio-responses while avoiding enzymatic degradation. In order to perform immobilization of these collagen-like molecules (CLMs) under mild reaction conditions, the bulk materials are first equipped with suitable surface groups using rf plasma methods. Plasma polymer interlayers offer advantages as versatile reactive platforms for the immobilization of proteins and other biologically active molecules. Application of a thin plasma polymer coating from an aldehyde monomer is particularly suitable as it enables direct immobilization of CLMs by reaction with their terminal amine groups, using reductive amination chemistry. An alternative route is via plasma polymer layers that contain carboxylic acid groups and using carbodiimnide chemistry. A third route makes use of alkylamme plasma polymer interlayers, which are less process sensitive than aldehyde and acid plasma coatings. A layer of poly-carboxylic acid compounds such as carboxylic acid terminated PAMAM-starburst dendrimers or carboxymethylated dextran is then attached by carbodiimide chemistry onto the amine plasma layer. Amine-terminated CLMs can then be immobilized onto the poly-carboxylic acid layer. Surface analytical methods have been used to characterize the immobilization steps and to assess the surface coverage. Initial cell attachment and growth assays indicate that the biological performance of the CLMs depends on their amino acid sequence.

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Model of vibration in drilling into fibre-reinforced composite materials

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/09544054jem1435 ◽

2009 ◽

Vol 223 (9) ◽

pp. 1107-1114

Author(s):

B W Huang

Keyword(s):

Composite Materials ◽

Vibration Amplitude ◽

Time Dependent ◽

Process Time ◽

Drilling Process ◽

Improve Product Quality ◽

Analysis Model ◽

Inhomogeneous Materials ◽

Reinforced Composite ◽

Twisted Beam

A model of the dynamic drill characteristics while drilling through fibre-reinforced composite materials (FRCMs) is investigated in this study. Anisotropic and inhomogeneous materials such as FRCMs, which are used to improve product quality, make it possible to improve production rate and avoid drill breakage. Such materials were used to study the dynamic characteristics of the drilling process. A theoretical analysis model for drilling composite materials is proposed. A pre-twisted beam is used to simulate the drill. A moving Winkler-type elastic foundation is used to approximate the drilling process time-dependent boundary. Numerical analysis indicates that the vibration amplitude changes significantly as the drill moves through composite material.

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