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Double shear strength of B.S.L.69 snap head rivets in L.72 and L.73 aluminium alloy sheet
No full textA limited series of tests has been carried out on
single and double shear riveted joints using 1469 (D.T.D.327)
snap head rivets and L.72 (D.T.D.610) and L.73 (D.T.D. 546)
sheets. The specimens were similar to those used by the
Royal Aeronautical Establishment (ref.1), the double shear
specimens being essentially two single shear specimens placed
back to back.
In each case the 1 per cent, 2 per cent and ultimate
strengths were found, the single shear values being in agreement
with the equivalent R.A.E. tests (ref. 2).
It was found that at high bearing stresses the
permissible shear stress in the double shear joint falls
below that of the single shear joint having the same nominal
bearing stress, This reduction of permissible shear stress
was found to increase with joint extension and to be
independent of the sheet materials tested. Design curves
are given
Combined pyrolysis and radiochemical gas chromatography for studying the thermal degradation of polymers
No full textPyrolysis gas chromatography and radioactive tracer techniques have
been used independently to study the thermal degradation of polymers. In
these laboratories the two techniques have been combined to elucidate
some of the mechanisms of the thermal degradation of epoxy resins and
polyimides. This paper describes the apparatus developed for this work
The application of information theory to parcel sorting
No full textThe work on parcel sorting was originally suggested to the
Materials Handling Research Unit by British Rail which is one of the sponsoring organisations contributing to the Research
Fund. This work has also formed the subject of a research thesis,
which has been used as the basis of this report. The
student, Mr. B. R. Degerlund is therefore the main author, in
co-operation with the staff of the Research Unit … [cont.]
Automatic assembly design project 1968/9: report of component supply and separation committee
No full textThis report outlines the techniques for automatically feeding the components of an electrical contact block and describes the design of a feeding system for each component. All components of the contact block were initially analysed for automatic feeding and redesigned where necessary. Existing feeding methods were examined and consideration was given to their versatility. Decisions were then made as to the feeding system for each component
An experimental method of determining the mean heat transfer coefficient for the nozzle of a solid propellant rocket engine, by means of constant flow calorimetry
No full textAn investigation has been made into the feasibility of predicting mean
convective heat transfer coefficients for the nozzles of solid propellant rocket
engines. The principle of the method used was constant flow calorimetry;
the surface of a copper nozzle was heated with a flow of hot water, and cooled
by air flow through the nozzle. Heat transfer coefficients were then derived
from measurements of water flow, water temperature drop and nozzle surface
temperatures. For a range of Reynolds numbers, the mean convective heat
transfer for a star-shaped conduit could be expressed by the following equation: -
Nu = 0.1976 Re
0.631
Pr
0.333
For a cigarette-burning charge the mean convective heat transfer could be
expressed by the following equation : -
= 0.7013 Re
0.491
Pr
0.333
The flow pattern into the nozzle was studied using a water flow visualisation
rig involving both photographic and direct viewing techniques. In addition,
investigations into the temperature and pressure distributions along the nozzle
surface at ambient conditions were carried out using a perspex nozzle fitted
with surface thermocouples and pressure tappings
Heat transfer through an incompressible laminar boundary layer
No full textThe study of the boundary layer theory has been done by reviewing briefly
the boundary layer concept, the boundary layer equations, and the exact solutions
for wedge flow.
All the methods for the calculations of the heat transfer coefficient are
surveyed briefly, describing their procedure and their limitations
Wideband measurement of transistor small signal parameters by time domain spectrometry
No full textTime Domain Spectrometry (TDS) Methods are outlined and their application
to measurement of transistor parameters is discussed. Experimental results
are presented and the advantages and limitations of TDS methods are re-assessed.
Future developments are suggested
Anisotropic creep in a glass-fibre laminate
No full textA glass fibre epoxy resin laminate was prepared from a flexible thermosetting resin and a 'plain weave' glass cloth. Experiments in
simple tensile creep were carried out on strips cut with their long
dimensions at various angles to the warp threads in the glass cloth. It
was found that each of these strips showed, over the limited range of
loads and times covered, essentially linear creep behaviour. The creep
compliance varied systematically with direction being as much as twenty
times smaller in the warp and weft directions as at 45° to these directions.
It was found that the shape of the creep compliance versus orientation
curves was similar for all times and the behaviour can therefore conveniently
be described by two curves, a master curve of reduced creep compliance as
a function of direction and a curve of reduction factor versus time.
The significance of both these curves is discussed in terms of an
extension of linear viscoelasticity theory to the case of antisotropic
materials. It is shown that the variation of creep compliance with
direction is similar in form to the variation of elastic compliance with
direction in orthorhombic anisotropic elastic materials and also that the
results are consistent with a similar variation of relaxation time spectrum
with direction
Characteristics of the high temperature mechanisms of creep and recovery in graphite: part 1
No full textAn apparatus has been developed for determining the high
temperature creep and recovery characteristics of graphite by applying
torsional stresses to thin-walled tubes. This method has the advantages
of a simple stress system, constant stress for constant load, easy
rapid removal of load and the independence of the strain measurement
from thermal expansion. Torsional, stress-strain curves show a decreasing
modulus with increasing temperature from 2000 - 2850°C. The rate of
creep in this range is increased by increasing temperature and stress.
Recovery rate is not so sensitive to increasing temperature. Using a
method developed for metals, where recovery can be subtracted from
forward creep, a secondary creep rate is deduced. This rate, when
plotted according to the Arrhenius' equation, yields an activation energy
for secondary creep of 154 kcals over the temperature range 2100 - 2700°C.
These results are critically examined and the future extension of the
work discussed
The longitudinal static stability of tailless aircraft
No full textThis paper describes the development of a simple theory of the longitudinal controls fixed static stability of tailless aeroplanes. The classical theory, as developed for the conventional aircraft, is modified to accommodate the particular features of the tailless aeroplanes. The theory was then applied to a particular blended-wing-body tailless civil transport aircraft, BWB-98.Cranfield Universit