FAIZURE ANAZYSIS CASE SZZLDIESII Edited by D.R.H. JonesPergamon doc

FAIZURE ANAZYSIS CASE SZZLDIESII Edited by D.R.H. Jones Pergamon [...]... some 2438 by 1524mm (8 by 5 ft “large frames”), others 1524 by 1457 mm (“small frames”), and a few smaller Each panel was bounded by a rectangular frame made of 50.8 x 50.8 x 6.35 mm (2 x 2 x 1/4in.) steel angle, welded at mitre joints at the corners The frame held a sheet of fire resistant composite, an 8.5 mm asbestos-cement core faced on both sides by 0.5 mm galvanised steel sheets, pierced by 6.35... the outer radius of the case, and rz (= 23.5 mm) is the inner radius of the case Since k , x 1760MPa for the case, the failure torque is 0.98 x lo7N mm The total torque is therefore (2.06+0.98)= 3.04 x 107Nmm It is interesting to notice that, even though the case is only 1.5mm thick, it is responsible for nearly one-third of the total torsional strength This is partly because the case is more than twice... accidents in connection with silos are due to suffocation or gas poisoning of the farmers entering a silo Some are also caused by the explosion of methane, which is produced by fermentation of the forage Cases of bursting or explosion are, nevertheless, rather rare In the present case, three identical silos had been built on a farm, each with a diameter of 6 m (20 ft) and a height of nearly 25 m (80 ft)... shear stress can be described by the empirical expression k, (MPa) = 700+8.78 x 10-3(r/mm)3 (6) over the core of the shaft (the region from the centre of the shaft to the inner edge of the case) The torque required to cause shear fracture of the core is then given by r = 27c 23.5mm 0 (700+8.78x 10-3r')r2drNmm=2.06x 107Nmm (7) The torque required to cause shear fracture of the case can be found from the... testing Figure 8 is a macrograph of the polished cross-section after etching in 2% nital The case- 15 Fig 8 Polished cross-section through the shaft, showing the case- hardened layer Table 2 Hardness measurements on shaft cross-section as a function of radial distance from the centre r (mm) HV 0 10 17.5 22.5 Case 350 360 375 400 880 (MW ~ T S 1120 1152 1200 1280 2816 k, (MPa) 700 720 750 800 1760 measured... tempered Table 2 shows that the hardness of the case (HV 880) is significantly higher than that specified (HV 68G780) However, there was no indication that this contributed to the failure As shown in Figs 3 and 4, the splines were able to withstand a considerable shear strain even though they were case- hardened The maximum engineering shear strain suffered by the splines was y = 1.3 mm/l5 mm =0.087 =... at the bottom to 2.4 mm at the top All in all, the silo consisted of 16 rings and one base ring The individual sheets had been protected against corrosion by enamelling, and were joined by bolts and nuts The joints were protected against corrosion by a special kind of mastic The total capacity of a silo was approximately 630 m3 Since the farm no longer had any use for the silos, they were rented to... Testsfor traces of an explosion Specimens F were subjected to laboratory tests to detect possible traces of heat influence by fire or explosion No such traces could be found Thus, one can conclude that failure was not caused by the explosion of methane or any other gas produced in the silo by fermentation 2.3 Tensile tests The sheet metal was tested using specimens BR, CR, BP and CP, as shown in Fig 6 and... complicated by the fact that the firewall was not intended to resist pressure, and that it contains elements of widely different strengths, with a limited capability to redistribute loads Complex structures of this kind are nowadays almost invariably analysed by finite-element methods However, for lcgal reasons that regrettably cannot be examined here, there were two independent analyses, one by hand calculations... was driven by a worm connected to the steering wheel The steering arm, which transmitted movement to the track rods, was attached to the end of the shaft by a splined connection As shown in Fig 3, the steering shaft had been subjected to a torsional overload As a consequence of the overload, the splined section of the shaft had been twisted permanently (the ends of the splines were offset by 1.3mm), . the interruption to service. According to the lorry driver, the silo had been, at that time, approximately three-quarters full, and the manhole lid had. catalog record from the Library of Congress has been applied for British Library Cataloguing in Publication Data A catalogue record from the British Library