An assessment on effect of process parameters on pull force during pultrusion.

This research investigates the process behaviour by prediction of the pull force required to drag raw materials through heated die during pultrusion with different reinforcing material configurations. Pultrusion is a continuous manufacturing process that is widely used for composite profiles. A device was designed to apply friction force by pulling on 'resin-impregnated' fibres, with both liquid resin and partially cured resin. This device was used to measure pulling force in conjunction with temperature and resin conversion. This enabled the experimental simulation of materials tracing for both short and long die lengths. Differential scanning calorimetry (DSC) was used to determine polymer conversion. The results show that the downstream part of a die has no significant effect on the pulling force before a certain degree of conversion is achieved. The research has also shown that higher resin conversion leads to higher friction in the viscous /liquid zone. The difference is much more significant when the temperature is low (e.g. room temperature), reducing when the temperature rises. A mathematical model predicts that increases in compaction pressure will have an impact on increasing fibre volume fraction and drag velocity, which is an opposing characteristic to tapping angle and considerations of part thickness. Similarly, many parameters - like shrinkage, viscous force and dry friction - were modelled and simulated for ortho polyester resins as a function of temperature and resin conversion during dynamic pulling. The study is directly applicable in configuration of pultrusion manufacturing; enabling customisation for a specific configuring material, components manufacturing and respective die design for the profile

Shock propagation behaviour and determination of Gruneisen state of equation for pultruded polyester/glass fibre-reinforced composites.

Polyester fibres reinforced with glass fibres hybridised polyester resin composite (PFR/GFHC) is a unconventional complex high-molecular weight crosslinked network polymer composite. This novel composite can be used in the manufacture of structural body parts for lightweight vehicles, armour vest for body protection as well as armours for vehicles. For body armour applications, it is important to determine the dynamic behaviour of PFR/GFHC during high velocity impact. In this work, we propose a method of calculating Gurneisen parameter from the measured Hugoniot in shock velocity – particle velocity of polyester based composites product by high velocity actuated nail gun impact. Several high-velocity impacts were conducted on pultruded plates using a power actuated nail gun with different cartridges and varying nail sizes. The experimentally measured Hugoniot in shock velocity – particle velocity space was determined as Us = 2.872 + 1.22Up (ρ0 = 1.25 g/cc) and low gradient observed for Gruneisen parameter as calculated from measured Hugoniot against V0/V shows higher shock absorption of PFR/GFHC for impact velocity

Advances in structural analysis and process monitoring of thermoplastic composite pipes.

Thermoplastic composite pipes (TCP) in comparison to other pipes have proven beneficial features due to its flexibility which includes being fit for purpose, lightweight and no corrosion. However, during the manufacturing of TCP which involves the consolidation process, certain defects may be induced in it because of certain parameters, and this can affect the performance of the pipe in the long run as the induced defects might lead to in-service defects. Current techniques used in the industry are facing challenges with on-the-spot detection in a continuous manufacturing system. In TCP manufacturing process, the pipe is regularly monitored. When a defect is noticed, the whole process stops, and the appropriate action is taken. However, shutting down the process is costly; hence it is vital to decrease the downtime during manufacturing to the barest minimum. The solutions include optimizing the process for reduction in the manufacturing defects amount and thoroughly understanding the effect of parameters which causes certain defect types in the pipe. This review covers the current state-of-the-art and challenges associated with characterizing the identified manufacturing induced defects in TCP. It discusses and describes all effective consolidation monitoring strategy for early detection of these defects during manufacturing through the application of suitable sensing technology that is compatible with the TCP. It can be deduced that there is a correlation between manufacturing process to the performance of the final part and selection of characterization technique as well as optimizing process parameters

EFECT OF VINCRYSTINE AND RHINOTOMY FOR NASAL TUMOUR IN A COW

A six year old Bengal non-descript pregnant cow weighing 200kg with a hemorrhagic tumour mass in right nasal cavity attached to nasal septum compressing the left passage was presented with stretor, unilateral epistaxis and difficulty in breathing. Administration of Lithium Antimony thiomalate at deep intramuscular route was not effective. Vincrystine @0.025 mg/kg I/V was without response. The growth was removed by dorsal rhinotomy. Diathermy and diluted phenol were used for separation and hemostasis, respectively. In histopathology, the mass was diagnosed as chondro-adenofibroma

<span style="color:black;mso-bidi-language:HI">Effect of interaction of commercial and nano size CaSO₄ filler on mechanical and thermal properties of polyurethane foam </span>

582-589Compo<span style="color:#080808; mso-bidi-language:HI">site foams were prepared by addin<span style="color:#080808; mso-bidi-language:HI">g different concentration (0<span style="color:#080808; mso-bidi-language:HI">.5-2.<span style="color:black; mso-bidi-language:HI">5 wt<span style="color:#080808;mso-bidi-language: HI">%) of commercial and nano size CaSO4 filler in a single-phase polyurethane matrix<span style="color:#272727; mso-bidi-language:HI">. The differential S<span style="color:#080808; mso-bidi-language:HI">canning Calorimeter (DSC) f<span style="color:#080808; mso-bidi-language:HI">or composite as well as pure pol<span style="color:#080808;mso-bidi-language: HI">yuretha<span style="color:black; mso-bidi-language:HI">ne was done to ascertain the degree of interactio<span style="color:black; mso-bidi-language:HI">n <span style="color:#080808;mso-bidi-language: HI">of filler with the s<span style="color:black; mso-bidi-language:HI">tructure of matri<span style="color:#080808; mso-bidi-language:HI">x as <span style="color:black; mso-bidi-language:HI">acti<span style="color:#080808;mso-bidi-language: HI">ve s<span style="color:black; mso-bidi-language:HI">ites or strong interaction with the matrix. <span style="color:black; mso-bidi-language:HI">The degree of cell formati<span style="color:#272727; mso-bidi-language:HI">on increases on increase in amount of nano filler in the composites whereas decreases in case of micron size filler in composites. The increment in specific gravity for nano size filler (0.17-0.3 g/cc) and in case of micron size filler (0.17-0.23 <span style="mso-bidi-font-family:Arial;color:black; mso-bidi-language:HI">g/cc) <span style="color:black;mso-bidi-language: HI">makes a strong support for the increment of cell numbers. The significant enhancement (300%) in mech<span style="color:#080808;mso-bidi-language: HI">anical properties, <span style="color:black; mso-bidi-language:HI">compressive strength, and the optical and transmission electron micrographs (TEM) of the cell sizes also satisfies the DSC results. The decrement in amount of heat (∆H cal/g)<span style="color:#080808; mso-bidi-language:HI">, in case of commercial size filler for curing, shows the conduction of heat is more due to formation of cells (less in numbers) that results in reduction of rate of heating. On increasing the am<span style="color:#080808;mso-bidi-language: HI">ount of filler in composites, specific gravity incre<span style="color:#080808;mso-bidi-language: HI">ases more in case of nano size in composites rather <span style="color:#080808;mso-bidi-language: HI">commercial size fi<span style="color:black; mso-bidi-language:HI">ller. Thermal Gr<span style="color:#080808; mso-bidi-language:HI">avimetric Analyzer (TGA) shows i<span style="color:black; mso-bidi-language:HI">ncrement in degradation temperature in case of nano size filler. Increment of flammabilit<span style="color:#080808;mso-bidi-language: HI">y for nano s<span style="color:black; mso-bidi-language:HI">ize filler (4<span style="color:#272727; mso-bidi-language:HI">.7-10.61 <span style="mso-bidi-font-family:Arial;color:#080808;mso-bidi-language: HI">s<span style="mso-bidi-font-family:Arial;color:black;mso-bidi-language: HI">/mm<span style="mso-bidi-font-family:Arial;color:#080808;mso-bidi-language: HI">) and in case of commercial size filler (4.<span style="color:black; mso-bidi-language:HI">7-6<span style="color:#272727;mso-bidi-language: HI">.15 s/rnm), shows <span style="color:black; mso-bidi-language:HI">th<span style="color:#080808;mso-bidi-language: HI">at the incorpo<span style="color:black; mso-bidi-language:HI">ration of nano p<span style="color:#080808; mso-bidi-language:HI">articles not only improves the degradation behavior but also retards the inflammable time. </span

Extended Near Wall Hindered Diffusion Theory for Nanoparticles under Short and Long Range Interactions

An extension of the near wall hindered diffusion theory of Brenner [1] is considered for spherical nano-particles undergoing Brownian motion under the influence of hydrodynamic drag and electrostatic interactions. Brenner\u27s theory is based on hydrodynamic interactions between a levitating particle and the wall and does not consider short range interactions (like electrostatic force and van der Waals force). Recent experiments by Banerjee & Kihm [2] (henceforth referred to as BK05), with nano-particles of radii ≤ 500 nm show substantial discrepancy between the experimental and theoretical values of normal reduction coefficient (ratio of near wall normal diffusivity to bulk diffusivity). However, the experimentally measured lateral reduction coefficient (ratio of tangential diffusivity of the wall to bulk diffusivity) show good agreement with theory. It is conjectured that the absence of short range interactions become critical for particle radii ≤ 500 nm in the (sub-micron) near wall region. The current work extends Brenner\u27s analytical theory (henceforth referred to as B61) considering various short and long range interactions. An analytical expression is derived for hindered diffusivity of a particle normal to the wall under the influence of hydrodynamic drag and electrostatic interaction with a constant surface charge density. The theory is validated with experiments of BK05 and shows a better agreement with measured values of diffusion coefficients for particles of radii 50 and 100 nm. The dependence of electrolyte concentrations on electrostatic potential energy for spheres has also been studied. Increase in ionic strength of electrolyte concentration confirms the reduction of electrostatic potential energy for different sphere sizes. Electrostatic interaction has a significant contribution in overall potential energy of the sphere in sub-micron near wall region when wall and sphere surface charge potentials are increased

Determination of cure mechanism inside die for a part manufacturing during large-scale pultrusion.

The cure kinetics of resin, heat capacity and thermal conductivity of reinforcing materials of uncured mass dictates the ultimate curing of reinforced thermosets manufactured component. In this study, degree of conversion from heat capacity by ‘Lumry and Eyring Model’ and order of reaction by multi-regression technique using ‘Borchardt and Daniels Model’ are calculated in finding cure kinetics (ɣ) of the resin. Experimental results from differential scanning calorimetry (DSC), thermogravimetry (TGA) and rheological measurements were used to determine thermal conductivity, heat capacity and rheological parameters of the resin through several model fitting. The calculated thermal conductivity of uncured composite from ration of (length vs contact area) and thermal resistivity extracted from TGA data was fitted into specific mathematical model which predicts the thermal behaviour of heated prepreg during pultrusion operation. These parameters used in a separate mathematical partial differential equation-based model equation to predict the change in temperature and resin conversion along axial distance and radial thickness. The influence of operating conditions, such as rate of heating (Early and late Heating) and fibre volume fraction while curing inside die were calculated and validated with experimental results. This study evaluates the extent of heat transfer and degree of conversion inside pultrusion die during scale up steady state process. It is observed that paradigm of influencing parameters like pulling speed, die radial thickness and heater engagement (Early and late heating) on heat flow from die wall to core (i.e., thickness of the part being pulled) follows the data captured experimentally

Numerical Modeling and Optimization of Hydrokinetic Turbine

Hydrokinetic turbines, unlike conventional hydraulic turbines are zero head energy conversion devices which utilize the kinetic energy of flowing water for power generation. The basic operational principle of the horizontal axis hydrokinetic turbine (HAHkT) is same as the wind turbine, the only difference being change in working media: water instead of air. This paper discusses the hydrodynamic design of HAHkT via numerical modeling. Presently these turbines suffer from low coefficient of performance (Cp) which is governed by several design variables such as tip-speed ratio, chord distribution, solidity and number of blades. The numerical modeling is performed for both constant and varying chord geometries using commercially available computational fluid dynamics software (CFX/FLUENT) to understand the effect of each of the design variable on turbine performance. Since the flow Reynolds number is large (≥ 105), both one - and two-equation turbulence models are applied to solve Reynolds Averaged Navier Stokes equations. In addition, a three dimensional analysis of HAHkT is performed to give a better insight into the effect of tip vortices and flow separation phenomenon on turbine performance; the results are then compared with Blade Element Momentum (BEM) theory analysis. In addition, a procedure for a multivariate optimization scheme is discussed that aims at maximizing Cp for a constant flow velocity while maintaining optimum values of critical design variables listed above. Finally, the effect of variation of angle of attack on the flow around a hydrofoil is investigate using both static and transient analysis, the transient analysis being performed by subjecting the airfoil to periodic oscillations. Copyright © 2011 by ASME

Numerical Modeling and Optimization of Hydrokinetic Turbine

Hydrokinetic turbines, unlike conventional hydraulic turbines are zero head energy conversion devices which utilize the kinetic energy of flowing water for power generation. The basic operational principle of the horizontal axis hydrokinetic turbine (HAHkT) is same as the wind turbine, the only difference being change in working media: water instead of air. This paper discusses the hydrodynamic design of HAHkT via numerical modeling. Presently these turbines suffer from low coefficient of performance (Cp) which is governed by several design variables such as tip-speed ratio, chord distribution, solidity and number of blades. The numerical modeling is performed for both constant and varying chord geometries using commercially available computational fluid dynamics software (CFX/FLUENT) to understand the effect of each of the design variable on turbine performance. Since the flow Reynolds number is large (≥ 105), both one - and two-equation turbulence models are applied to solve Reynolds Averaged Navier Stokes equations. In addition, a three dimensional analysis of HAHkT is performed to give a better insight into the effect of tip vortices and flow separation phenomenon on turbine performance; the results are then compared with Blade Element Momentum (BEM) theory analysis. In addition, a procedure for a multivariate optimization scheme is discussed that aims at maximizing Cp for a constant flow velocity while maintaining optimum values of critical design variables listed above. Finally, the effect of variation of angle of attack on the flow around a hydrofoil is investigate using both static and transient analysis, the transient analysis being performed by subjecting the airfoil to periodic oscillations. Copyright © 2011 by ASME

Numerical Investigation and Evaluation of Optimum Hydrodynamic Performance of a Horizontal Axis Hydrokinetic Turbine

The hydrodynamic performance of horizontal axis hydrokinetic turbines (HAHkTs) under different turbine geometries and flow conditions is discussed. Hydrokinetic turbines are a class of zero-head hydropower systems which utilize kinetic energy of flowing water to drive a generator. However, such turbines very often suffer from low-efficiency which is primarily due to its operation in a low tip-speed ratio (4) regime. This makes the design of a HAHkT a challenging task. A detailed computational fluid dynamics study was performed using the k- shear stress transport turbulence model to examine the effect of various parameters like tip-speed ratio, solidity, angle of attack, and number of blades on the performance HAHkTs having power capacities of ∼12 kW. For this purpose, a three-dimensional numerical model was developed and validated with experimental data. The numerical studies estimate optimum turbine solidity and blade numbers that produce maximum power coefficient at a given tip speed ratio. Simulations were also performed to observe the axial velocity ratios at the turbine rotor downstream for different tip speed ratios which provide quantitative details of energy loss suffered by each turbine at an ambient flow condition. The velocity distribution provides confirmation of the stall-delay phenomenon due to the effect of rotation of the turbine and a further verification of optimum tip speed ratio corresponding to maximum power coefficient obtained from the solidity analysis. © 2011 American Institute of Physics