UC-NRLF B 3 flS3 flSM FEDERATED .MALAY STATES. REPORT ON THE RESULTS OF MECHANICAL TESTS CARRIED OUT ON SOME MALAYAN TIMBERS BY H. T. M. KENT, A.M. INST!, C.B., A.C.G.I., A<:t in i/ Timber Superintendent, Federate! M' dait? 5». /lie belief that they may be of practical use t/o-'AitJg^eTK. •*•/!• 2 : /. **•. ••'•••• ::..:.•• •....• B. H. F. BAENAEI), Acting Conservator of Forests, F.M.S. and 8.8. i. - Forestry - REPORT ON THE RESULTS OF MECHANICAL TESTS CARRIED OUT ON SOME MALAYAN TIMBERS. No reliable data has boon published of the mechanical properties of the Malayan timbers and tho lack of such has been frequently commented upon. It is with a view to supplying some approximate figures relating to the properties of the local timbers that these notes are put together. Originally the tests were made on a few selected timbers to determine their suitability or otherwise for use in aeroplane construction and it was intended that the tests should be of a preliminary nature only, and that specimens of timbers thought to be suitable would be sent to England to have tests of a more detailed nature carried out upon them. It was soon found that the result of the tests might be of more general use than for the specialized purpose originally intended, and the scope of the investi- gation was therefore enlarged and the figures tabulated below are taken from tests made on 689 specimens. As noted above the tests can only be accepted as of a preliminary nature for although some considerable care has been taken to make the tests as accurate as possible yet the lack of a suitable machine and suitable measuring apparatus has been severely felt. A further difficulty in obtaining suitable seasoned material has necessitated a number of unseasoned specimens being used in the test, rendering strict comparison between the various tests difficult. On the other hand the tests may be said to have been made on material similar to that used in good general construction, and may therefore be accepted as a guide in future design. '2. The tests were carried out on specimens in cross bending and the results are therefore most applicable to beams used to resist bending moments. No tests were carried out under Compression, direct shear or impact nor was any attempt made to compare the hardness of the various timbers as the machine available was not adaptable for such tests. For purposes of comparison it should be noted that the tests were carried out on specimens approximately 2" x 1" in cross section and the results reduced to the recognized square inch basis. This is mentioned as it has been found that results obtained from small specimens are in general higher than those obtained from specimens of a larger cross section. All tests were carried out on an " Avery " 2-Ton Machine using the "three point suspension" method; the specimens being loaded centrally and supported on rigid supports 18" on either side of the centre. In general the loads were applied by hand in \ cwts. increments at the rate of 1 ton per hour. The deflections of the beam were measured after each increment of load and were determined by the movement of the timber at the point of load. No allowance has been made for local crushing which was small in most cases. The apparatus to hand did not permit of a more accurate determination of the deflection. The curve connecting load and deflection for each^jae^mfin^w^s plotted and the yield point maximum load. en-.. determined from the curve, the constants given for each timber being reduced to the square inch basis of comparison. 3. The weight per unit volume of timber was calculated from measurements and weighings of the whole test piece (some 80 cubic inches in volume) made at the time of test, and reducing the weight per unit volume so obtained, in the ratio of the weight of a small piece (2J" long cut at a standard distance of 6" to 8f" from one end of each specimen) weighed immediately after being cut to the weight of same piece after having been oven dried. Thus the weight per cubic foot tabulated is the weight in Ibs. of a specimen of the wood oven dry which was one cubic foot in volume at the time of test. Owing to the shrinkage which takes place in wood when it is dried the figure so obtained is not the true weight per unit volume of a piece of oven dry wood. This is, however, the method generally adopted of determining the weight of timber. The specific gravity can be obtained by dividing each result by <>2j (approx.). The air dry weight of an}' of the timbers can be obtained by adding 12 per cent, to 15 per cent, to the oven dry weight. 4. The results of the tests have been grouped together in batches, each batch bpin«' composed of several specimens obtained from one tree and the average, maximum and minimum figures (excluding results obtained from damaged specimens) for oven-dry weight elastic limit, modulus of elasticity and modulus of rupture have been tabulated. By comparing the average with the maximum and minimum figures given an idea of the reliability or otherwise of the limber can be obtained. The strength of an}' wood (the modulus of rupture) appeal's to bear a distinct relation to its weight. This relationship is fairly well expressed by the linear equation: R = .1.5-1- w " R " being equal to the modulus of rupture in tons per square inch and " w" being the oven dry weight of one cubic foot of the timber. An equation which is more cumbersome to use, but which appears to express the relationship rather more accurately is of the form n R=a w " a " and " n " hei'iiii1 constants. Too few tests have as yet been made to definitely determine the best values for "a" and "n" but it appears that the equation 1.25 " 1U.S salaried the plotted values fairly well. 5. Several notes are appended regarding the general behaviour of the timbers tested and it is hoped that these may be of value. The note.- arc not intended to In- exhaustive but are results of observations marie on the specimens when under test. It should be noted how in general the air-dried specimens are stronger than those which contain more moisture. LIST OF WOODS USED IN MECHANICAL TESTS. Batch No. Common name. Latin name. 1 2 3 4 Damar Minyak Seraya— No. 86 Seraya— No. 106 ... Nyatoh Agathis alba Shorea Curtisii Shorea Curtisii Palaquium sp. 5 Biiitan^or Calophyllum sp (! Bintan^or . Calophyllunx sp Nyatoh Bniiffor Palaquium sp. Lafferstroemia sp 9 10 Merawan ... Kun^kur Hopea sp. Albizzia sp H Dedali Strombosia javanica 12 13 14 15 16 17 18 19 Dedali Snnai or Mersawa... Medang Tanclok ... Medang Chengal or Penak... Chengal or Penak... Keranji MerawRii Strombosia javanica Anisoptera sp. Litsea ? sp. Litsea sp. Balanocarpus sp. Balanocarpus maxim us Dialium platysepalum Hopea sp OQ Belian Payena utilis 21 Betis Payena utilis 22 Punggai Coelostegia Griffithii 23 Ru Casuarina equisetifolia 24 25 26 27 28 29 30 81 Perepat Tempinis ... Pulut Pulut Keladan Hesak Kapur Perian Tualano1 Sonneratia sp. Sloetia sideroxylon Ficus sp. Dryobalanops sp. Shorea barbata Dryobalanops aromatica Artocarpus rigida KooTnpassia parvifolia 32 Rengas Melanorrhoea ^ sp 33 34 35 36 Bakau Minyak Kapur Keruing Kulim Rhizophora conjugata Dryobalanops aromatica Dipterocarpus sp. Scorodocarpus borneensis 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 Kungkur ... Muntelor ... Merawan ... ... ... Keledang Penaga or Lenggapus Meranti Kait Kait Berangan ... Jelutong Jahor Petaling Gajah or Kamap Pagar Anak Kelat Seraya Batu Petaling Gajah or Kamap Merbau Tempinis ... Albizzia sp. Parinarium sp. Hopea sp. Artocarpus lanceaefolia Mesua ferrea Shorea sp. Castanopsis sp. Dyera costulata Cassia siamea ? Ixonanthes icosandra Eugenia Ridleyi Shorea sp. ? Intsia (Afzelia) sp. • Sloetia sideroxylon 53 54 55 Damar Hitam Damar Laut Daun Kechil Damar Laut Daun Besar... Balanocarpus penangianus Shorea sp. 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Inc. J Stockton, Calif. T. M.Reg. U.S. Pat. Off. *j M17875 THE UNIVERSITY OF CALIFORNIA LIBRARY A.TI