The equipment describedin this manual is manufacturedand distributed by TBCQUIPMENT LlMITBD Suppliers of technologicallaboratory equipment designedfor teaching. Tel: (0115)9722611 : Pax: (0115)9731520 @ TecQuipment Limited No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage and retrieval system without the express permission of TecQuipment Limited. Exception to this restriction is given to bona fide customers in educational or training establishments in the normal pursuit of their teaching duties. Whilst all due care has been taken to ensure that the contents of this manual are accurate and up to date, errors or omissions may occur from time to time. If any errors are discovered in this manual please inform TecQuipment Ltd. so the problem may be rectified. A Packing Contents List is supplied with the equipment and it is recommended that the contents of the package(s) are carefully checked against the list to ensure that no items are missing, damaged or discarded with the packing materials. In the event that any items are missing or damaged, contact your local TecQuipment agent or TecQuipment direct as soon as possible. CONTENTS Specification 1. Introduction 2. Unpacking 3. lacking of 4. Forces due 5. load 6. Cell 1 and Assembly load to 2 4 Cells Dial 7 Calibration 9 Experiments 6.1 Support reactions simply-supported 6.2 Variation of beam with load, Verification Influence Simply beam 9 of a simply-supported beam thickness of the theory for pure fixed 18 21 beam with 28 supports central prop a cantilever Propped cantilever (with rigid 6.10 Propped cantilever (with elastic - about a principal beams 31 33 6.9 of bending 25 of Bending 14 theory Deflection Sheet material deflection beam with supported and of of reciprocal line Continuous for a point-loaded, deflection Demonstration formula 5 Gauges 36 prop) prop) axis 40 43 r SPECIFICATION Load Cells 3 off, 0-40 and locking Dial Gauges .3 off, N capacity screw 0-25 for mm in with adjustable converting 0.1 to divisions knife rigid mounted edges supports. on magnetic carriers. Spring Balance 1 off, 0-10 Weight Hangers 4 off, fitted 6 off, 10 N; 4 off, Weights Cantilever Support 1 off, able Beams 3 Services Required Space Required with rigid for nwn cursors. 5 N; 4 off, pillar all steel, 1350 N capacity. test 1 with 2N. clamping arrangement suit- beams. 1 aluminium, brass, mmwide and all19 long. NOr..l:. Bench the area approximately apparatus 2 x 0.6 can span two small m. Alternatively, benches of the same height. Ancillaries The SMlO4a tributed cells, supplied Specimen loads, dial to Beams, SMI04b uniformally SMIO4c moving gauges, order. hangers Quote serial loads, and/or additional weights number of disload can be equipment when ordering. NOTE SPBOMBNS The dimensions stated for specimensare for reference only. To ensure the accuracyof experimental results and calculations,it is recommendedthat all specimensare measuredprior to experiments. c -1- 1. INTROOl£TION The SMl04 Mk III Beam Apparatus of experiments to the bending of beams. to cover virtually ing beams on simple the beam. with hangers allow allow supplied Three 6 alloy Beam the whole and all fourth for the , clamping one end of the basic up to four unit. deflections length Apparatus almost any experiment bending under of along action dial at three the beam. rour gauges points. measurement Five beams are of these are 19 mmwide and 1350 mm long. one each of thicknesses (Note: with involving of These, supports. and three beam is made of brass 6 mmthick 6 mm thick. the with relating for mount- gauge along the upper cross-member allows standard mm; a facilities at up to four points of requirements and also for provide of the beams are mild steel, aluminium The loading along as provides are supplied unit, which extend the range coursework supports measurement a dial deflection and the clamping simultaneous Traversing of or sinking point all The basic unit Three load cells together has many features point 3 rom, 4.5 mm and the fifth of these are nominal dimensions). its ancillary the investigation loads, equipment distributed can be used for of beams subjected loads, moving to loads and couples. Additional hangers, equipment dial TecQuipment. gauges, such as load special cells, beams clamped and loads supports, are weights available and from f -2- 2. UNPACKING AND ASSEMBLY 2.1 l.h1packing 1. Remove all to of the components from their discard any packing material packing, until taking care not the Packing Contents list has been checked. 2. all Unwrap bench. amongst accounted The main of the and transport The packing the costs. tee material with face for sny tighten One the the of which the the will two rear lower head. until other carry lower the two the the be acale upper components Use washers whole frame not and the use. (the the face back of with under all This member is are at holes, one each side Again front tighten up the six nuts. and the upright fitt- and do not legs. when all four attached the rear the back of tee and, forward has two brackets two members to the the the nuts these fron for a washer Bolt through be bolted brackets front brackets the as follows: should member. of to minimise has been assembled. cross-members in on it should to the order proceed holes bolted face in frame The scale beams not members the graduated head should bolt nuts dismantled inwards). should The bolt below the through cross-member members. supplied To assemble legs members the ed SMlO4 is cross-member lower 3. the the Packing Contents List. for. frame to 2. components and lay them out on a suitable Assemly packing 1. the Check the components against Check 2.2 of legs nuts through pass are of the the the bolts in place, ~ -3members in be clamped washer clamp 4. The the the the tee the 6. The or stored cells. plastic plastic Before fitting but the do The load cells should knob down and placing knob should legs. not can These whichever clamp can top the apparatus weights until load a 'C' now be wound up to cell. apparatus, beam The run on the from loading the gauges magnets The winding it. load dial removed 5. by above magnets. the same way as the dial discard the can is and are held position remove the them. Whenever the mounted be fixed either the convenient. more keepers by from gauges are must be replaced. on rods at in gauges keepers be stored be attached required. rail one end in of front the on the of or feet of behind beam apparatus m -4'"- J. LOCKING (T LOAD CELkS The knife the locating cell body locating NOTE: t-- edges of screw load knife load cells cells supplied (as shown in rig the The the can be locked through 0.1). Note in position the OIl rest plate the OIl should edge. will by screwing into the load be removed before n" ,; be locked for shipment. r~ l rig 0.1 -5- 4. In fORCES the charts the load cell dial gauge. Zero the the the flat SlCMly dicated gauges GAU(l:S . it (fig dial gauge is dial Ensure spring raise that marker. on the balance. Repeat A graph of be linear. force crocodile (say of allow top of the the crocodile gauge (fig procedure, against clear the gauge this is with balsnce done to the will Attach by top the using load exert- calibration clip cross member or the obstructions. the required unit clip to Zero This until the the movement. attached. balance it is is knurled done level part of 0.3). until s convenient 5 rom) and note increasing deflection include follows: properly the to best O-ring spring dial is the of the dial the as gauge contact balance contact necessary This fitted or unscrewing zero is 0.2). may be constructed and the screwing with DIAl experiments dial which Ensure by TO load-sensitive ed by ~ Dl£ should the the deflection reading deflection be drawn. on the is in- spring each time. The graph should -6- J [ r Fig 0.2 Dial Gauge -urig 0.3 Spring Balance Attachment L l fig 0.4 Calibration of Load Cells -7- 5. LOAD CELL CALIBRATION The three beam A load as shown in locked this to read knife set zero. span (do not found using using the ensure cell The Tap the on the value (e.g. dial the cell deflect with when the the the always load due to and adjust dial gently cell B so that and take at B is °10 N) and then Plot W/2. edge A and adjust load the beam at mid- hanger, height of is load to a calibration which can be knife edge B to zero. This is to perpendicular cell Increase decrease beam above the gauge again load the loaded; dial gauge returns and the cell the the the load beam is on the read zero. horizontal frame load of at B to balance) until gauge to rest height include at each step. should identify curve load requires is not beam horizontal supported reading. the zero, to load The to some taking the the particular curve for other load load B. to typical to spring beam procedure care load thumb wheel reading load cell The the exerted maximumm will the up a simply gauge on the beam above knife adjust forget beam. force and by setting set Now move the Set the the rirst support up a dial B reads 0.4. the zero. edge can be calibrated rig so that done, the cells is each shown cells a then force can be seen by the are of in be repeated calibration fig the curve with its cells, own load taking cell. A 0.5. calibrated 2 N. position for so that 1 mm of downward displacement The number of revolutions of marks below the main load cell the rest plate relative body, as shown in rig of the dial to the indication 0.6. gauge -9~ 6. It EX~~J~~I~ is possible, TecQuipment bending ing especially is of obtained, beams experiments 1. 2. and can ed in detail to cantilevers and Verification of Demonstration for Simulation of a rolling Continuous beam with 9. Deflection a point-loaded supported of of fixed beam with Propped cantilever with elastic As stated quoted 6.1 Support Reactions 6.1.1 Introduction ---simple for but themselves by beam supported starting the it at mid-span the thickness the dimensions manual of student set the experiment the specimens using suitable Simply-supported which apparatus 1/4-span measure beam. specimens For accurate should be measuring and Beam allows its students sensitivity up as shown diagrammatically l/4-span of the the supplied). experiment the of are nominal. a Point-loaded, is and at the and width (not with at prop the useful The apparatus Before prop dimensions instruments the load, prop this the measured with beam with bending earlier, in results accuracy. supported a cantilever 11. familiarise pure central rigid a beam supports with is describ- load cantilever This are follow- deflection Propped Note: and the theory 10. Experimental unit The simply-supported a simply of reciprocal lines Simply involving apparatus. basic from pages. theory Influence 8. experiment SMlO4 the available beam material the of equipment any the using deflection beam thickness almost out for of cdditional using be carried reactions Variation the perform in the following Support 3. 4. 5. 6. 7. if to and in Fig 1.1 points. the points length for of the beam and mark easy reference. Measure r -10- r Arrangement of Supports Fig 1.1 6.1.2 EQuipment Two load the and Loads ReQuired cells, one dial gauge, two load hangers, the weights and one of beams. 6.1.3 Procedure 1. Choose the a suitable reading mid-span of on the the beam. upper scale of the apparatus for (One of the 10 cm markers is most convenient). 2. Set up of of 3. one the any of the marker offset in the position in 4. Place 5. Position Lock the the beam in load position may press so step that 1. it (Do is not 1/4-span forget to the left to take account of the mid-span cursor). cell knife two hangers (The cursors cells chosen Set up the second reading. load 1/4-span to the right edge. with equidistant lightly 1. 1/4-span from against overhang at the mid point the scale). either end. of beam. the L -11- 6. Place a dial the ball rests on the centre-line of end the bottom dial gauge to the dial very read the the cell 6.1.4 Theory to the 2 to the read readings 1 lock the above the and take Resolving cross the moments about 1.2 R2 gauge reads knife a systeinatic of the graphs load to edges. manner, Move check adjust the zero. Adjust the tap the beam cells. illustrate the theory. 2 . . . . 1.1 R2 : + WZ(!£ - b) + W18 - W2b . . . . 1.2 1 in support, the + W !(W1 + W2) R positinn. and vertically; RiR. = Wi (!R. + a) Therefore Adjust member, then dial both vertical zero. in plot bezel right-hand WI + Wz - Rl R2 = Therefore: stem is in hangers and beam immediately and then gauge and unlock results the member so that stem. edge so that to the cross has been moved down the the = w R + R Substitute Check that parallel indicators to Fig 1.2. 1 is dial gently Process zero knife loads 9. a-ring beam of Apply support. gauge to a position the Remove Taking upper the load Refer on the left-hand height 8. position above the that 7 gauge in 1.1: = !(W1 + WZ) - W1a/.Q, + Wzb/.Q, . . . . 1.3 -13- 6.1.6 {::omparison Substituting following the table is with Theory value of R., a and b in equations obtained: Fig 1.2 Theoretical arrangement 1.2 and 1.3, the -14- 6.2 Variation of Deflection Beam Thickness 6.2.1 of,a theory of book and shows only in the pure bending that of a beam can be found when a beam is plane of the applied the bending I the second is moment of Modulus R is the radius a is the bending stress at y is the distance from the close approximation, is deflection of of by the Using equation 2.2 jected to direct loading the of a is a constant of the and . . .2.1 beam section inertia) it y from beam at the neutral axis axis curvature of derivative distance x from a beam l/R of the is given, deflection. a chosen origin = 1 = M R can be shown that can always to a If z the be expressed deflection in the of form: B-~' value . . . . 2.3 El depends load acting on the beam upon the type [ a beam sub- deflection whose [ then: . . . . 2.2 EI supports W is the neutral second z = the distribution . distance the dx' z is bends curvature ~ where it Elasticity shown that of stress R area the be a way that text moment E is also the such any standard by (moment can in moment, y I H is loaded in = -a = ~ H the Beam with load and Material curvature of the beam are related It orted Theory The where Sim 1 of loading and l. -15l is [ and I is the relationship .2 the span are defined Equipment load above investigated in this experiment Required cells, one dial gauge, one hanger, set of weights, all of .the beams. 6.2.3 1- 4 5. Procedure As for experiment 1. Place the at hanger centre-line 6. 7. of Exactly as Place read 8. dial zero Apply the Do this the deflection at Repeat 12. For each the gradient For the step Taking N/m2 and a graph at each the the five is on the the ball end Adjust the of the dial to the beam deflection dimensions on the dial on the gauge are new dial gauge reading (deflect- times. the for same steps all a graph as 9 and record the beam of beams l/d' (d the beams. deflection plot is N/m2, values gradient of against load. Determine graph. 21 X 1010 the point step. steel 12 against of that setscrew. record scale record by each three using so the and the least load of = of hanger experiment ES span loading bezel. and beam plot the the m. load Decrease mid centre the the 10 11. 14. to that 1. at Note:- mm i.e. Increase in lock a load ion). 13. on the and so beam. gauge gauge. 0.1 sp~n experiment rests dial 9. for the plunger the mid the a graph thickness EB = 10.5 obtained obtained of for in step the of x 1010 the gradient the beam). N/m2, 6 mm thick 12 against obtained EA = 7.6 beams, l/E. x 10 plot -16- 6.2.4 Analysis of Results [£FlECTION z (mm) LOADW (N) STEEL 6 mm STEEL STEEL BRASS 4.5mm 3 mm 6 mm 5 10 15 20 25 30 Table 1 rig 2.1 results Steel shows in tables the and Brass typical Table 2 Beams shape of graphs obtained Aluminium by plotting Beam the 1 and 2. Steel -EE -E -u 0 .- "OJ, \4Q, C - c 0 .- OJ Q' [. -E c. /Steeli..5mm /~.Bross 6 mm u QI - " /",'" .~,,'" /,,'". /~ .{/ . Steel 6 mm /' """""'" ,,~ 10 20 30 W(N) -17- 6.2.5 Conwnents The graphs The transverse of the For as in of lines the proportional the rig 2.2 accordance to straight lines for all beams can be determined stiffness in obtained nn] from five from beams. the slopes x 10-'). fig 2.1 can be recorded below. 6 mm beams, in are = W + [deflection beams the table the stiffness stiffness/(thickness)' three lIE of (stiffness Theoretically i.e. vs load stiffness five the deflection l'/I. z/W v lIE the slope with of a beam is = constant. of the the lines theory. pro.portional of to (thickness)', fig 2.2 shows that, fig 2.1 The slope are of for proportional this line the to is -186.3 Verification 6.3.1 Introduction - The theory for Experiment that equation 3.1, the Theory of Pure (section is bending is of The object measured by the obtained h(2R - h) = 82 2Rh - h2 a2 in 2.2: 1 Therefore Two the load this at experiment the start is to of show method. from which the h2 is Referring to relationship: usually very small 1 = ~ 82 = ~ h and M = ~ [I R Equipment outlined Sagital is R rig of curvature Therefore Also from Equation was valid. curvature radius to 6.2). ie 6.3.2 r' Bending [ 2.2 of the a beam subjected 2 The radius rig of = . . . . 3.1 Wa1b/2EI rig 3.2 3.1 l Required cells, beams preferably three dial gauges, two hangers, set of weights, one of L 6 mm thick. l L -19- 6.3.3 Procedure To set up constant the apparatus bending so moment over that the the middle beam is subjected of length half its to a follow steps 1 to 4 of experiment 1. 5. one hanger near the left-hand Place load is applied on the centre-line hanger at the right-hand the same distance 6. Place one dial of the beam. at mid-span and side of it 7. Adjust the 8. Apply equal loads to the two hangers 9. Gently tap as shown in fig the gauges beam near to its (See fig the other the hangers are 3.2). two equidistant on 3.2. either dial Place the second end of thhe beam so that from the supports. gauge three end of the beam so that the read zero. mid-span and take the readings of the dial gauges, h , h , and h . Increase 11. the values of W. Process the load results and repeat as shown in steps the 8 and following 9 for example at least five -20- r . . 6.3.4 Analysis of Results Beam - Brass, Y = !(h.. 6 mm thick 1350 mm long [ + h3) r w (mm) 300 100 300 100 300 100 300 100 300 100 5 300 150 10 300 150 15 300 150 20 300 150 25 300 150 5 300 200 10 300 200 15 300 200 20 300 200 25 300 200 Test 1 Test 3 a (mm) (N) Test 2 b hI h2 h3 (mm) (mm) (mm) y (mm) h 2-Y (mm) [ [ 1. 6.'.5 ~ The Calculations straight equation ~ since line 3.1) from graphs against this obtained by W show that equation the plotting equation gradient is: 3.1 h2 - Y (this is of the is correct h in form, ~ 2EI ~ Thus when b is 300 mm ( = .3m) the gradient = ~1!: [1 ~ Therefore for constant against a2 should flexural rigidity The second moment b (in be linear of the of area this and its case 0.3 gradient will the above give of gradient a measure of the beam. of the beam = 19 x 6' = 3.42 x 10-10 12 x 10 'I ~ Using m) a graph EI = results: m~ .15a2 gradient Therefore: ~. = E Grd. 6.4 Demonstration of Reciprocal 6.4.1 Theory to Referring simply N/m2 .1582 x I Theory fig 4.1a, it can be shown that the deflection beam AB with supported Zo point load W at C is given by: = Web (L2 - 82 - b2) . . . . 4.1 6l It is seen i.e. changed, ion ""- at that r is the if the the at D of the value loading same as the of z will is as shown in deflection not at D. change rig if 4.lb, a and bare then the interdeflect- r-22If the will beam is be reciprocal theory the same as the theory should now loaded which is be referred as shown in deflection rig at demonstrated to in a standard 4.lc D. in then This this is the deflection a particular experiment. at.G case The general textbook. of r (a) A [ rig 6.4.2 Equipment Two load cells, 4.1 Reciprocal Theory Required three dial gauges, three hangers, weights, one beam. -23- L 6.4.3 Procedure 1-4 Exactly 5. '" as in Experiment 1. Place load hangers and dial gauges as shown in fig 4.2. and b need not be equal but are equal in the example below.) 6. Use one of the dial Return the dial 7. 8. 9. 10. Apply a three dial Move the gauges to go through gauge to its suitable original record the readings of all gauges. load to the other of all three Various combinations dial of two hangers in turn loads can be applied the readings of all Use results demonstrate to three dial the and inter-changed gauges. the reciprocal ,,~~...2I4Q~..1.1.. '-'-' and record gauges. recording ..'" ~I ~~:~.~.'Wl."'\1/. .. L/4- . t- -Lf4- ~ fig 4.2 Demonstration of Reciprocal ,~ 1. position. load to any hanger, readings the step 6 of experiment below~ " (Note: a Theory theory as shown -24- 6.4.4 Analysis = a W h = = of Results = 200 b Load (N) deflection WI J.J. 1.1.1. iv (mm) a) WI (mm) (mm) (N) 5 0 0 0 10 0 5 0 W2 (mm) h2 W3 (mm) (N) h3 (N) 5 0 5 0 0 15 0 0 10 iv h3 Wa 0 10 ii .5 (mm) TWO POINT LOADS b) Examination of R~sults Comparison of reciprocal theory to points 1 the deflection is of part that h2 SINGLE POINT LOAD hi (N) 6.4.5 Wz (N) 0 5 0 0 i ii (mm) hI (N) 1 mm Examination results and the a(i), applies 3. a(ii), to points Comparison doubled b results and a(iii), 1 and 2, of results when the will applied verify will to points a(i) the is that 2 and 3 and also and a(iv) load verify will doubled. following: verify L -25- from a) (i) the These (ii) additional From b) and (i) ing the two values the additional 10 N at and (iii) the additional x point deflections x additional deflection to applying at 1, due to apply- 2 = ~. a g ree should 2 2 due 1 = Xl" 10 N at point 1 and at to within a very small be clear that percent- age. results From c) applies theory it will 6.5 Influence 6.5.1 Introduction The the position of ion of the obtained by the the for point the between due the which and 3 and from apply to points deflection of a unit applying of 1 should reciprocal results b(iii) and 2 and 3. Deflection for application it be seen to relationship example to the the load the acting of line a point deflection application principle influence of on a beam is of on the that point beam. of any load superposition of and the The deflectto the after by the magnitude a line beam is multiplying the load. (See follows). Equipment Two load points also line ordinate 6.5.2 and b(iv) to line influence showing b(ii) Required cells, dial 6.5.3 Procedure 1-4 As for 5. Set gauge, experiment up the hanger, weights, one beam. shown in fig 5.1 1. equipment as with the as for experiment 1. values of load cells locked. 6. Carry out 7 Vary the record the the levelling value dial operation .of W for chosen gauge readings. a and b (fig 5.1) and r -26- 8. for each increment 9 Plot of (see the results). influence line the defined 10. set Apply given as the a load by readings incremental system determine for load. mean deflection The 'unit' per may be load. and compare calculation 'unit' the based the measured on superposition deflection and the with that influence line. Fig 5.1 Schematic of Experimental Set-up l Fig 5.2 Influence lines for W = 5 & W = 10 N 6.5.4 Analysis of a = 200 mm h k = at = /5 deflection [(h Results W=5 - deflection N (mm) (mm) h at W=0)+5]+[(h at W=lO - h at W=5)+5] ...etc . These results can be presel,ted 6.5.5 Example 1. 10 N applied in of Application at b to of the Deflectio~ due Deflection due to 5 N Measured obtained 10 N It Influence as in Line with = 2 x k at 450 = k at 250 (mm) for fig 5.2. W= 5 5 N at b 250 mm = (mm) = 2 x k at 450 + k at 250 (mm) Deflection above. form 450 mm together = Total Deflection The graphical is then should compared be found that with the the total two figures deflection are in close agreement 2. 5 N applied at b = 400 mm together Deflection due to 5 N Deflection due to 10 N Total Again the total deflection. Deflection measured = deflection with 10 N at b = 200 mm k at 400 (mm) = = 2 x k at 200 (mm) k at 400 + 2 x k at 200 (mm) should be in very close agreement with the t r -28- 6.6 Continuous 6.6.1 Introduction A great from the amount this of backlash. It of care experiment. heights difficulty Beam with in is knife errors as shown in the fig ~2 W Rl 6.1, - the reading the of load the be obtained adjustment load cells cells can lead of for to results. for a continuous beam carried on rigid that: 3 (S2 + b2) 16 + b) (s . . . . 6.1 . . . . 6.2 o. 5 - .t!2 . . . . 6.3 ~ = 2 - ftl- ft, W W R. . . . . 6.4 w ~~~ 6.1 to to accurate Wa B., w rig of are = 0.5 - ~2 W .B.2 good results must be paid can be shown from the theory supports, if edges and correction in interpreting Supports required Attention the Small rixed Ra R. Continuous Beam on 3 Supports -29- :1: 6.6.2 Three 3 1. Equipment load Required cells, three Set up the load the Place the 3. Place a hanger 4. Set 5. Place the a two hangers, the O-ring Move dial upper weights, so at equal of each one beam. of from the overhang part of at the will either end, span. If stem it requires the Set the Rl they span. above Rl. stem so that beam. 1/3 so that zero position part that positions and to down the gauge edge middle pointers the O-ring. ends with gauge in move the knife convenient its the cell made. with the at position at dial on Move the be beam in load O-ring cells beam near 2. 6. gauges, Procedure support .L dial to zero, R2 and dial it gauge the allows lock adjuust just gauge has no one fitting. contact just to the bezel, do NOT the height of contacts the the beam, no further. 7. Repeat 8. Repeat that 9. just 'U ~ 5, the Place dial ~~t" 6 with 6, load gauges dial cells then the dial place the displace at the indicate on the contacts just gauge and 7 until O-rings to Place the part gauges the (There load loads on the of at Rl' cell gauges. equal beam is horizontal, making sure zero. upper beam. R,. hangers. the stems of the R2 and R, so that should be sufficient indicator.) Set the remaining the ball pressure zeros of -3011. Adjust the regained height with the 12. Repeat 10 and 6.6.4 Analysis of of dial the knife gauges 11 until edges so that then sufficient take the results contact load have cell been is just readings. obtained Results BEAM Steel 6 mm thick ARRANGEMENT Refer t~. to fig 7.1 400 8 mm b 800 RIll . 6.6~5 Calculated Substituting following the results Value~ values are of and (8) in equations 6.1 to 6.4 the obtained: !1 W = 0.5 - 125 = 400 !, = 0.5- ~ = 0.1875 0.3438 800 w fl.2 (b) = 2 - 0.1875 - 0.3438 = 1.4687 W Comparing be seen that the above values there is close with those agreement. obtained by experiment it should -31- Simply theory ferred 7.1 Beam with C!!!tral Prop Theory .} The Supported to in it beams supported for the can standard by rigid textbook. be shown that the or elastic For force the props should configuration induced in the be re- shown in rigid prop is Fig given by: 1.375 W p It can also . be shown that -11 x Wl' the deflection at mid-span 6.7.2 Three 6.7.3 Equipment load .7.1 . . . . 7.2 Simply Supported Beam with Central Prop Re~ired cells, dial gauge, two hangers, weights, one beam. Procedure Carry not out Arrange 6. lower lock Place the essential 5. 7. . is: [1 Fig 7~1 . to the the the usual other a dial support hangers knife setting as shown edge two gauge the at knife at up procedure beam at in mid-span fig so the but 1/4 in this case and is points. 7.1. that it is clear of edges. mid-span it set it to read zero. the beam. t -Jl- 8. 9. Apply 10. Measure Set the ~ loads to to the zero. 12. Alter 6.7.4 Analysis the two with down with the middle the edge Record load of at a finger knife the load cell to zero. hangers. deflection contact Adjust 11. on the the in edge Steel pointer mid-span. knife edge. whilst the by screwing load cell Make sure If necessary deflection up until press is the the beam is the knife measured. dial gauge returns reading. 9 through repeating that 12 as many times as required. Results beam 6 mm thick; 19 mm wide; W (N) span 1200 rom; 1=342 Deflection z (mm) P' (N) very with (mm)4. P/W 5 10 15 20 25 6.7.5 Comments 1 P/W = 2} From equation should agree closely E 7.2: = 11 384 Therefore: E 11 384 x 5 x equation 7.1. [ x ~' Iz 1200' 342 x z = 72.368 x 1& N/rnrn2 z l. where W = 5 N L -33- of a Cantilever Deflection 6.8.1 Introduction Reference to the for a cantilever textbook will show that the deflection under the load loaded at the free end is given by: z = Wl' . . . . 8.1 3EI If EI and l are maintained constant then: z = k .W 1 . . . . 8.2 z = . . . . 8.3 where k 1 is constant Similarly if [I and Ware likewise z = ~, E J It follows and z = ~ if constant: k2l' E and I respectively are made I the that therefore between relationship maintained experiments the deflection illustrated below can be carried and each of the variables. out showing quantities the E, I, l and W. In the experiment Note Since large, the edge due to of the cantilever a load the dial cell Clamped support, 6.8.3 Procedure 2. is of the Land upwards. for high be taken Ware cantilever made to deflect gauge should Equipment .. deflection only upwards accuracy into varied. due to self weight by screwing the the loading of is knife the beam account. Required one load (Refer Set up a load the frame. Set up the clamp cell, one dial gauge, one beam or more. to Fig 8.1.) cell to at give a convenient a cantilever position of near convenient to one length. side of -34- 3. Pass one on the end of load cell. assembly). using 4. Set 5. the Adjust the load 6. cell. Adjust the recording 7. edge; slacken more convenient 8. Repeat 9. In it so that of load the edge knife the order the and load vary and lock tie rest the up the dial and the clamp than moving for E use to to clamp end of the the knife other edge free end of set the zero. end during the beam dial give cantilever, gauge Hove unlock returns a convenient dial give to the zero. gauge reading on the reading. a number of load increments readings. its initial and move the load several the the and zero. the gauge edge the to to upwards experiment to cell upwards edge loads the to adjust knife Return near free Record to and the knife clamp string. to and pointer clamp of the convenient gauge gauge edge is the dial dial knife (It piece the the beam through Tighten a short Place the position; it to lock a new position the (this knife is cell). lengths Aluminium, of Brass cantilever. and Steel beams 6 mm thick. 10. In order to vary I use the steel beams 3 mm, 4.5 mm and 6 mm thick. rig 8.1 Schematic of Experimental Set-up r -36- 6.8.4 Typical Results BEAM Steel l r~ 6 nIn thick (mm) 200 W (N) 400 300 z (mm) z (mm) 500 600 z (mm) z (mm) z (mm) 2 4 .6 '8 10 6.8.5 Comments The each L' of graphs length z v W verify that equation given by the respective the a graph gradients obtained of z L' = graphs is a measure equation 8.2 is correct, with with k1 for The graph of z v of the graph. 8.3 is correct, gradient the v give in 8.1: of x/W will substituted rrom equation being given by the gradient verifies If that k2 for each load being of the graph. for z/W are plotted, the of the obtained gradient flexural for of rigidity each length the of straight the and line beam when 8.1. W-' 3£1 JEI = ~' z since I = 342 mm4 then:- E = inverse of Qradient 3 x 342 N/mm2 -376.9 Propped' C"antilever 6.9.1 Introduction The theory standard for a ProD) propped beams and cantilevers cantilever free end it the loaded can be referred to in most as shown in rig 9.1 with a rigid the prop is prop deflection at the free end, 2 6 if absent, is given . . . . 9.1 prop the force in the prop is: P=~ w . . . . 9.2 16 the its z = for a rigid Since at can be shown that: by: b) Riaid textbooks. ror a) (with deflection of z = a cantilever loaded at its free end is given by PL' 3[1 then P, Wand a are related PL' = WL' by the equation: (3cl . . . . 10.3 - C2 where c In this experiment the relationships given in = all equations 9.2 and 9.3 investigated. w !.z J. T!'c:; fig 9.1. Loaded Cantilever L ~ Supported by Rigid Prop at End are r -38- r rig 6.9.2 load Equipment cell, beam*, * end due 6.9.3 1. to of self Set the alIen screws one in of aluminium the free cantilevers. so that knife a cantilever edge. of beam in knife edge. member of the clamped. clamp, (See fig gauge on the position lock and replace zero. short the the members. read the of the cross the of deflection Remove the clamp to use the position. tightly a dial but approximate on the lightly with and it 6 mm thick 9.2) its upper clamp only cross Clamp, a convenient at rests the contact and set the and support the is Place rig at clamp to required lower to cell end parallel beam may be used can be accommodated. locate top Weights, necessitates (Refer up a load that J. material loading Procedure Hanger, edge. other I m long 2. Gauge, straight A beam Set-up Experimental ReQuired Dial steel 9.2 four the the clamp so that the frame then replace the screws so that the alIen Now, with set the Ensure the a rule length of beam and lock held the beam is cantilever the the bezel. to the clamp l vertically clamp as to the 9.3.) beam as close lock recess four as possible t 4. the dial Unlock the knife edge gauge reads zero. (Note: pointer is Remove gauge and place it on the beam above the knife edge. 5. 6. zero slide the dial watch the pointer). Place the dial load 7. 8. the cell Place Adjust its that the whole position height the and not +100 or -100 gauge in so that 0 - indicated divisions. length above the the of If the knife dial by the necessary, cantilever and edge and set the to zero. hanger the adjust Be sure gauge along pointer the and in height position. of the knife edge so that the dial gauge reads zero. 9. 10. Record Add the a obtain load load at cell to least the Remove the weights 12. Place the apply a suitable Adjust zero 14. hanger the Now place the and repeat at 0.2 load and repeat of the (e.g. of the the load steps B, 9 and 10 so as to results. and hanger height and record hanger five 11. }). reading. load at 0.4 step 6. span (measured from the clamp) and 8 N). knife cell edge so that the dial gauge reads reading. of the span and repeat for 0.5,0.6 and 0.8. 15. Either the plot results graphs in tabular to verify form equations as shown in Fig 9.3 10.2 the and 10.3 example or arrange below. r -40- 6.9.4 Analyais of Results [ = Part 2: L Note: from i.e. w = = 1000 mm w equation PIc. 9.7 9.3: = 0.5 500 nwn c N iW(3 - c) PIc! I (1.5 - O.5c) I w -iii ~ c P 0.2 O.J 0.4 0.5 0.6 0.8 1.4 1.35 1.3 1.25 1.2 1.1 PIc! 1.5-0.5c W Error ~ 6.9.5 Conwnents The average values of ~ from part 1 agree with equation 9.2, ~W C The results experimental also that of Part errors the 2 verify occur load cell equation reading number then the reading c are highly magnified o when the larger = 0.2 p 5 J..e. - = -> W 16 load for for c 9.3 cell and show that is c = 0.2 = 0.8; compared with lightly the loaded. are multiplied therefore the same errors greatest Notice by a much small errors at c = 0.8. at L -41(With ProPped Cantilever 6.10 Prop) Elaatic 6.10.1 Introduction Referring to applies in equations the introduction the present applying zw = W [1 ~ b) If prop force i) the experiment case and is to a cantilever a) the to 9, restated loaded here equation as the as shown in fig is P then: of = the cantilever due to the prop deflection obvious difference between i.e. and if that a = the of = the prop due to the prop force cL . . deflections - p w = 3c2 of given the prop must be equal by 10.1 to and 10.2. Zp (3c2 6EI whence 10.3 of the prop. deflection w..' then: is: f. the zw ~ is: . . . . lC wher~ k is the stiffness is force -PL' K It the 8' deflection ~ of 10.1: XI the first still 6"" 2 zP ii) 9.1 - c~ 2 + (6EI/kl') - C') = f. k JE1 Pt.' = constant . . . .10.4 the r -42- 6.10.3 EQuipment Load cell, beam, steel ReQuired dial gauge, hanger, weights, clamp, 6 mm thick aluminium straight-edge. 6.10.4 Procedure 1-9 10. Exactly Add the same as for successive loads deflection and load 11. Remove the load 12. Compare the experiment 6.10.5 Analysis The of stiffness of to the cell hanger recording and repeat of the that 9. the values of load, reading. and hanger value with experiment Modulus obtained in experiment B (see of Elasticity step obtained note). in this 11. Results the load cell (elastic prop) is easily determined (see page 3). The experimental The results set-up can was shown in rig be presented in tabular 10.2. form as shown below. 6.10.6 Ca~!J_lations From equation 11.4 L. p w = i~_~__Q~21)-- O.~' (6EI/Id.') + 2 . . . . 10.5 ~ -43- 0.625 (6EI/~') J. From the above ~= ~ table 6W I, for the equations beam used in 10.5 and 10.6 ~ + 2 5 the . experiment, is and substituting E = D.625 . x 5 values x ;;J; .! .l ~ ..t .J using k and l: x 1.46199 x Iff N/mm2 ~p result 8) will 'c:t: I, 10.6 6 x 342 l...ll1 - 2 The ~ of . 3 x 1000' ~p J . 342 (mm)~, therefore, the - 2 . in close from give step another 11 of value agreement with for the procedure the Modulus the value obtained (i.e. carrying of Elasticity above. out which experiment should be -44- BENDI~- OF BE.A1'1S ABOU1A PRINC1~LAXIS ~ L ~ DEFLEalONEND AT 'X' SLOPE RfACll0 N MOMENT MF ~ .w WL3 IW Wa2b2 3EIL Wab(L+b) 6EIL r SwL4 384EI -'ilL3 24E1 [ ~ a t: MF b ~ ~F . Wa3b3 3'fj"'[3"- Wab2 wlL. 384[1 wL2 [L- MF ~ WL2 }W Wl L w 4r"""""-"""" ~x wLL. wL3 ru wl2 ill 2 ~ Rcgistered office Bonsall street Long Eaton Nottingham NGIO 2AN England National Tel International Tel National FAX International 880-29783 H: 9/96 FAX -~ ITEM PART No QTY -43 1 DESCRIPTION -- 2~ 4 4 4 "6 ,. r ~ 25481 ~ - ~ -. 25482 - 25486- - TQD~l ~rr>ciia Sheetf~ Acti~ 25487-=-' " lliSl-= 25552-' 15 16 17 18 CHECK I C~evef-supriiirt 2 1 1 1 5 -- ,...' j 13 01159722611 1159722611 01159731520 ~1159731520 ~ Clay_I>esl~t 1 6mm-A/F A11~nKey 1 1 i 1 - , 57812 57877 -- ,,~ Signed I I r~--~ ~--=~-- Sheet 1 of 1 MITCHELL PACKAGING LTD P.O. Box 16. Alma Palk I~strial Es~I.. GtanIIaIn. ~. NG3 t tSF. Telephone (0476) 74747 (8 hi) T...: 377885 MITPAJ<G. Fax: (0476) 77444 PACICAGWG MATERIAlS MANUFACTURERS & DlSTReuTOAS DaisyS~ W~. Gt-. Une. Sheffield 53 8SG. 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