scholarly journals Effect of Helical Winding Angle on External Pressure based Buckling of Partially Filled Thin Composite Cylindrical Shells

2019 ◽  
Vol 69 (4) ◽  
pp. 313-319
Author(s):  
A P Dash ◽  
R Velmurugan ◽  
M S R Prasad
Keyword(s):  
Solid Propellant ◽  
External Pressure ◽  
Filler Material ◽  
Linear Effect ◽  
Aerospace Application ◽  
Helical Winding ◽  
Glass Tubes ◽  
Series Of Experiments ◽  
Volumetric Loading ◽  
Winding Angle

Effect of helical winding angle on buckling load of thin composite tubes is investigated in this work.  Experiments are conducted on both empty and partially filled S2 glass tubes to estimate contribution of strength to the tubes by the filler material.  Chosen filler material mechanically simulates behavior of typical solid propellant used in aerospace application.   FE analysis with non-linear effect correlates well with the experimental data.  Three series of experiments are conducted to quantify effect of helical winding angle and increase in volumetric loading fraction(VLF).  Results confirm appreciable improvement in strength of filled tubes for higher VLF.  For the chosen pattern of winding, lower winding angle provides more strength to the tubes against external pressure buckling.   

scholarly journals 3D Numerical Modeling of Laser Assisted Tape Winding Process of Composite Pressure Vessels and Pipes—Effect of Winding Angle, Mandrel Curvature and Tape Width

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2449 ◽  
Author(s):  
Amin Zaami ◽  
Ismet Baran ◽  
Ton C. Bor ◽  
Remko Akkerman
Keyword(s):  
Temperature Distribution ◽  
Bonding Temperature ◽  
Considerable Effect ◽  
Pressure Vessels ◽  
Process Temperature ◽  
Thermoplastic Composites ◽  
Transfer Model ◽  
3D Numerical Modeling ◽  
Helical Winding ◽  
Winding Angle

Advanced thermoplastic composites manufacturing using laser assisted tape placement or winding (LATP/LATW) is a challenging task as monitoring and predicting nip point (bonding) temperature are difficult especially on curved surfaces. A comprehensive numerical analysis of the heat flux and temperature distribution near the nip point is carried out in this paper for helical winding of fiber reinforced thermoplastic tapes on a cylindrically shaped mandrel. An optical ray-tracing technique is coupled with a numerical heat transfer model in the process simulation tool. The developed optical-thermal model predictions were compared with experimental data available in literature to validate its effectiveness. The influences of winding/placement angle, mandrel curvature and tape width on the incident angles, the laser absorbed intensity, and the process temperature distribution are studied extensively using the validated model. Winding/placement angle has a considerable effect on the temperature distribution. Increase in winding angle results in a higher temperature for tape due to more reflections coming from the substrate. On the other hand, substrate temperature decreases as the winding angle increases due to a decrease in the laser incident angles based on the local surface curvature. An increase in mandrel curvature results in higher nip point temperatures for substrate and lower one for tape. Different mandrel sizes for 90 ° placement path do not have a strong effect on the substrate process temperature as for other winding angles because of less curvature change of the corresponding irradiated area. Tape width causes local temperature variations at the edges of the tape/substrate. In order to obtain the desired process temeprature during LATW or LATP processes, the laser intensity distribution on the tape and substrate surfaces should be regulated.

The effect of anaerobic pre-treatment on the inert soluble COD of fermentation industry effluents

1995 ◽  
Vol 32 (12) ◽  
pp. 35-42 ◽  
Author(s):  
G. Yilmaz ◽  
I. Öztürk
Keyword(s):  
Treatment Plant ◽  
Anaerobic Treatment ◽  
Baker’S Yeast ◽  
Full Scale ◽  
Operating Conditions ◽  
Baker's Yeast ◽  
Series Of Experiments ◽  
Pre Treatment ◽  
Process Wastewater ◽  
Volumetric Loading

The objective of this study is to determine the inert soluble COD of wastewaters from the fermentation industry. In this context, a series of experiments were performed for various effluents from baker's yeast industry including raw process wastewater, anaerobic pre-treatment plant effluents, domestic and washing waters mixture. The inert COD ratio (SISO) for the raw effluents from baker's yeast industry was determined as 0.1. This ratio was in the range of 0.20 to 0.30 for the anaerobically pre-treated effluents. TheSISO ratios for the wastewater simulating the effluent of the existing full-scale aerobic treatment plant have varied from 0.18 to 0.48. Such a large variation has been originated from the operating conditions of the existing full-scale anaerobic treatment plants. The higher volumetric loading rates and shorter sludge retention times correspond the lower SISO ratios for the full-scale anaerobic treatment systems in general.

Numerical Solution of Solid Propellant Transient Combustion

1979 ◽  
Vol 101 (2) ◽  
pp. 359-364 ◽  
Author(s):  
D. E. Kooker ◽  
C. W. Nelson
Keyword(s):  
Numerical Solution ◽  
Burning Rate ◽  
Solid Propellant ◽  
External Pressure ◽  
Finite Amplitude ◽  
Stable Model ◽  
Final State ◽  
Numerical Predictions ◽  
Numerical Solution Methods ◽  
Solution Methods

Three thermal theories of solid propellant combustion, [1, 2, 3], all based on the quasi-steady flame assumption, were subjected to a rapidly rising external pressure field simulating a gun combustion chamber. Transient burning rates were computed by four different numerical solution methods; the best results were obtained with an invariant imbedding scheme. The numerical predictions show that (1) burning rate “runaway” is a numerical difficulty and is not a solution to the models, (2) the final state of an intrinsically unstable model at constant pressure is composed of repeating finite-amplitude spikes, and (3) the dynamic burning rate from a linearly-stable model can be many times greater than r = apn.

Influence of Delamination on Strength of Externally Pressurized Glass/Epoxy Cylinders

1999 ◽  
Author(s):  
Peter Davies ◽  
Leif A. Carlsson
Keyword(s):  
Impact Damage ◽  
Compressive Load ◽  
External Pressure ◽  
Cylinder Wall ◽  
Failure Pressure ◽  
Filament Wound ◽  
Local Reduction ◽  
Delamination Resistance ◽  
Cylinder Strength ◽  
Winding Angle

Abstract The delamination resistance of filament wound glass/epoxy cylinders has been characterized for a range of winding angles and fracture mode ratios using beam fracture specimens. The results reveal that the fracture resistance increases with increasing winding angle and mode II (shear) fraction (GII/G). It was also found that interlaced fiber bundles in the filament wound cylinder wall acted as effective crack arresters in mode I loading. To examine the sensitivity of delamination damage on the implosion behavior of cylinders, external pressure tests were performed on filament-wound glass/epoxy composite cylinders with artificial defects and impact damage. The results revealed that the cylinder strength was insensitive to the presence of single delaminations but impact damage caused reductions in failure pressure. The insensitivity of the failure pressure to a single delamination is attributed to the absence of buckling of the delaminated sublaminates before the cylinder wall collapsed. The impacted cylinders contained multiple delaminations, which caused local reduction in the compressive load capability and reduction in failure pressure.

Experimental Analysis of Kenaf Filament Wound Tubes under Axial Compression Load

2014 ◽  
Vol 660 ◽  
pp. 778-782
Author(s):  
Iqbal Mokhtar ◽  
Mohd Yazid Yahya ◽  
Ab Saman Abd Kader ◽  
Shukur Abu Hassan
Keyword(s):  
Compressive Strength ◽  
Axial Compression ◽  
Compression Test ◽  
Compressive Load ◽  
Compression Load ◽  
Filament Wound ◽  
Filament Wound Composite ◽  
Glass Tubes ◽  
Winding Angle ◽  
Early Indication

The objective of this study was to determine the strength of kenaf filament wound tubes under axial compression load. Kenaf is natural reinforcement fibre in which need to explore its capability to replace and compare with other common commercial reinforcement materials. Axial compression test was performed as early indication to identify the performance of kenaf filament wound composite tubes. Comparisons have been done towards basalt, e-glass and carbon tubes using polyester as a resin. Axial compression test of kenaf/polyester and kenaf/epoxy tubes were conducted with different winding angles involved which are 450, 550, 650 and 750. The result shows the 450 kenaf/epoxy tubes generated the higher compressive strength followed by other winding angle in the ascending order. The layer strength identification have been conducted in 550 winding angle sample in which indicate the increment layer of winding is uniform between one, two and three layers in ascending orders. Comparison between the different reinforcement materials show carbon tubes produced the higher compressive strength followed by e-glass, basalt and kenaf. Kenaf/epoxy recorded 38.7% lower the e-glass tubes. Kenaf/epoxy tubes were observed to identify the improvement from kenaf/polyester tubes and results shows at least 22% increment have been generated. It can be concluded that kenaf presence as a reinforcement material was successfully combine as composite system under axial compressive load as well as lead to the promising indication to be introduced in low load bearing application.

scholarly journals XVIII. On repulsion resulting from Radiation.—Part II

1875 ◽  
Vol 165 ◽  
pp. 519-547 ◽  
Keyword(s):  
Electrical Resistance ◽  
Royal Society ◽  
Vertical Plane ◽  
Glass Tube ◽  
Normal Pressure ◽  
Small Tube ◽  
Glass Tubes ◽  
Series Of Experiments ◽  
Repulsion And Attraction ◽  
Very High

The present paper is in continuation of one which I had the honour of reading before the Royal Society, December 11th, 1873, and which was published in the Philosophical Transactions, vol. clxiv. part 2, page 501. In that paper I described various pieces of apparatus, chiefly in the form of delicate balances suspended in glass tubes, by means of which I was enabled to show attraction or repulsion when radiation acted on a mass at one end of the beam, according as the glass tube contained air at the normal pressure, or was perfectly exhausted. At an intermediate internal pressure the action of radiation appeared nil . Towards the end of the paper 1 said (70), “I have arranged apparatus for obtaining the movements of repulsion and attraction in a horizontal instead of a vertical plane. Instead of supporting the beams on needle-points, so that they could only move up and down, I suspend them by the centre to a long fibre of cocoon-silk in such a manner that the movements would be in a horizontal plane. With apparatus of this kind, using very varied materials for the index, enclosing them in tubes and bulbs of different sizes, and experimenting in air and gases of different densities up to Sprengel and chemical vacua, I have carried out a large series of experiments, and have obtained results which, whilst they entirely corroborate those already described, carry the investigation some steps further in other directions. I have introduced two important improvements into the Sprengel pump which enable me to work with more convenience and accuracy. Instead of trusting to the comparison between the barometric gauge and the barometer to give the internal rarefaction of my apparatus, I have joined a mercurial siphon-gauge to one arm of the pump. This is useful for measuring very high rarefactions in experiments where a difference of pressure equal to a tenth of a millimetre of mercury is important. By its side is an indicator for still higher rarefactions; it is simply a small tube having platinum wires sealed in, and intended to be attached to an induction-coil. This is more convenient than the plan formerly adopted (51), of having a separate vacuumtube forming an integral part of each apparatus. At exhaustions beyond the indications of the siphon-gauge I can still get valuable indications of the nearness to a perfect vacuum by the electrical resistance of this tube. I have frequently carried exhaustions to such a point that an induction-spark will prefer to strike its full distance in air rather than pass across the 1/4 inch separating the points of the wires in the vacuum-tube. A pump having these pieces of apparatus attached to it was exhibited in action by the writer before the Physical Society, June 20th, 1874.

The Buckling of Cylindrical Shells Under Longitudinally Varying Loads

1962 ◽  
Vol 29 (1) ◽  
pp. 81-85 ◽  
Author(s):  
V. I. Weingarten
Keyword(s):  
Compressive Stress ◽  
Solid Propellant ◽  
Cylindrical Shells ◽  
Longitudinal Direction ◽  
External Pressure ◽  
Circular Cylinders ◽  
Shear Load ◽  
Curvature Parameter ◽  
Axial Compressive Stress ◽  
The Stability

Two problems illustrating the effect of nonuniformity of loading on the buckling characteristics of circular cylinders are investigated. The first problem deals with the effect of linearly varying axial compressive stress, such as would be produced by the weight of the propellant in a solid-propellant engine case. The results indicate that the ratio of the maximum critical compressive stress induced by the shear load to the critical uniform compressive stress varies from 1.9 for the curvature parameter Z equal to 0 to 1.0 as Z becomes infinite. In particular, the increase in stress is less than 20 per cent for Z greater than 100. The stability of thin cylinders loaded by lateral external pressure, varying linearly in the longitudinal direction, is also investigated. The results indicate that for Z greater than 100, the buckling coefficients are proportional to Z1/2.

scholarly journals Biodistributions of air-filled albumin microspheres in rats and pigs

1994 ◽  
Vol 299 (2) ◽  
pp. 437-443 ◽  
Author(s):  
P Walday ◽  
H Tolleshaug ◽  
T Gjøen ◽  
G M Kindberg ◽  
T Berg ◽  
...  
Keyword(s):  
Ultrasound Contrast Agent ◽  
External Pressure ◽  
Shell Material ◽  
Albumin Solution ◽  
Air Bubble ◽  
First Order ◽  
First Order Kinetics ◽  
Ultrasound Contrast ◽  
Series Of Experiments ◽  
Pulmonary Intravascular Macrophages

The air-filled microspheres of the ultrasound-contrast agent Albunex are unique in that the walls consist of human serum albumin molecules which have been made insoluble by sonication of the albumin solution. The microspheres were isolated by flotation, and the washed microspheres were labelled with 125I. The labelled material was cleared from the circulation mainly as particles, not as soluble albumin molecules. In rats, 80% of intravenously injected microspheres were cleared from the blood within 2 min. Nearly 60% of the dose was recovered in the liver, only 5% in the lungs, 9% in the spleen, and negligible quantities in kidneys, heart and brain. Of the radioactivity in the liver, more than 90% was taken up by Kupffer cells (liver macrophages). The protein in the liver was degraded apparently with first-order kinetics (half-life 40 min). In pigs, over 90% of the intravenously injected dose was recovered in the lungs. The vastly increased recovery in pig lungs, compared with that in rats, is probably due to the pulmonary intravascular macrophages of the pig; macrophages are not normally found in this location in rats (or humans). In a separate series of experiments in rats, the biodistribution of shell material from the microspheres was examined. The microspheres were made to collapse by applying external pressure on the suspension, leaving sedimentable protein material consisting of layers of insoluble albumin from the ‘shells’ surrounding the air bubble. The ‘shells’ and the microspheres were cleared from the circulation and taken up by the liver with the same kinetics. In the lungs, a higher proportion (15%) of shells than of microspheres was recovered.

scholarly journals On the velocity of rotation of the electric discharge in gases at low pressures in a radial magnetic field

1907 ◽  
Vol 79 (532) ◽  
pp. 417-427 ◽  
Keyword(s):  
Magnetic Field ◽  
Electric Discharge ◽  
Vertical Section ◽  
Glass Tube ◽  
Radial Magnetic Field ◽  
Vacuum Tube ◽  
Glass Tubes ◽  
Series Of Experiments ◽  
Low Pressures ◽  
A Current

The following paper contains an account of a series of experiments on the motion of an electric discharge in a magnetic field perpendicular to the direction of the discharge current. The fact that the discharge moves in a magnetic field like a flexible conductor carrying a current was discovered long ago, and De La Rive showed that it could be made to rotate continuously round one pole of a magnet placed inside the vacuum tube. The apparatus used in the present experiments was similar in principle to De La Rive’s, but was arranged so that fairly exact measurements of the various quantities concerned could be obtained. Fig. 1 shows a vertical section of the vacuum tube and magnet used. The tube consisted of two concentric glass tubes cemented with sealing wax into aluminium discs. The discs had grooves turned in them to fit the glass tubes, and the part of the discs between the tubes projected a few millimetres, so that there was no danger of the discharge passing through the sealing wax. Polished platinum rings were fixed on to the aluminium discs between the glass tubes, and these formed the electrodes between which the discharge was passed. The ends of the tubes were carefully ground truly perpendicular to their axes, and the two platinum rings were accurately parallel. To keep the electrodes cool, a ring of narrow brass tubing was soldered on to the back of each disc and a stream of water was kept flowing through these whenever a discharge was passed. This arrangement enabled comparatively large currents to be used without softening the sealing wax. A narrow copper tube was soldered into one of the discs and communicated with the interior of the vacuum tube through a fine hole. The tube was connected by a mercury sealed joint with a glass tube leading to a bulb containing pure phosphorus pentoxide, a Töpler pump, and a McLeod gauge.

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