From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparative analysis of the properties and performance of light alloys (Aluminium, Magnesium) versus steel components.
| Identifier | ExFiles\Box 154a\1\ scan0276 | |
| Date | 8th March 1940 | |
| LIGHT ALLOYS VERSUS STEEL COMPARATIVE PROPERTIES OF LIGHT ALLOY AND STEEL COMPONENTS. MAIN ASSUMPTIONS. | | STEEL | ALUMINIUM. | MAGNESIUM. | |---|---|---|---| | DENSITY - LBS/CU.INCH. | 0.283 | 0.099 | 0.065 | | FATIGUE LIMIT - TONS/SQ.IN. (FORGINGS). | 12.0 | 8.0 | 6.0 | | YOUNGS MODULUS - LBS/SQ.IN. x 10^6 | 30.0 | 10.0 | 6.0 | | TORSION MODULUS - LBS/SQ.IN. x 10^6 | 12.0 | 4.0 | 2.4 | | COEFFICIENT OF LINEAR EXPANSION PER °C. | 0.000013 | 0.000023 | 0.000025 | | COEFFICIENT OF THERMAL CONDUCTIVITY-CAL{Mr Calvert}/CM^3/DEG C/SEC | 0.12 | 0.35 | 0.32 | LINEAR PROPORTIONS OF SIMILAR CROSS SECTIONS AT MAX PERMISSIBLE STRESS. | | STEEL | ALUMINIUM | MAGNESIUM | |---|---|---|---| | TENSION OR COMPRESSION. | 1.00 | 1.22 | 1.41 | | BENDING, TORSION, VIBRATION. | 1.00 | 1.32 | 1.50 | | SLENDER COLUMNS. | 1.00 | 1.42 | 1.58 | COMPARISON OF BEAMS. FIGURES FOR MAGNESIUM IN BRACKETS. BEAMS OF CONSTANT WIDTH. | BASIS OF COMPARISON | 1.00 STEEL (EQUAL DEPTH) | 1.00 ALLOY (1.00) (EQUAL STRENGTH) | 1.22 ALLOY (1.41) (EQUAL STIFFNESS) | 1.44 ALLOY (1.71) (EQUAL WEIGHT) | 2.80 ALLOY | |---|---|---|---|---|---| | WEIGHT | 100 | 35 (23) | 44 (33) | 52 (40) | 100 | | STRENGTH | 100 | 67 (50) | 100 | 187 (146) | 520 (950) | | STIFFNESS | 100 | 33 (20) | 61 (57) | 100 | 730 (1650) | | DEFLECTION | 100 | 300 (500) | 163 (176) | 100 | 13.3 (6) | BEAMS OF SIMILAR FORM. | BASIS OF COMPARISON | 1.00 STEEL (EQUAL SECTION) | 1.00 ALLOY (1.00) (EQUAL STRENGTH) | 1.15 ALLOY (1.26) (EQUAL STIFFNESS) | 1.32 ALLOY (1.50) (EQUAL WEIGHT) | 2.09 ALLOY (1.58) | |---|---|---|---|---|---| | WEIGHT | 100 | 35 (23) | 47 (37) | 62 (52) | 100 | | STRENGTH | 100 | 67 (50) | 100 | 153 (169) | 315 (455) | | STIFFNESS | 100 | 33 (20) | 58 (50) | 100 | 264 (380) | | DEFLECTION | 100 | 300 (500) | 174 (200) | 100 | 32 (26.2) | GENERAL COMPARISON. | KIND OF STRESS | MAIN ASSUMPTION | RATIO OF MAIN DIMENSIONS | AL/STEEL | MG/STEEL | MG/AL | RATIO OF SECTIONAL AREA | AL/STEEL | MG/STEEL | MG/AL | RATIO OF WEIGHTS | AL/STEEL | MG/STEEL | MG/AL | RATIO OF STRESSES | AL/STEEL | MG/STEEL | MG/AL | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | TENSION AND COMPRESSION | SAME ELONGATION OR COMPRESSION | sqrt(Eh/El) | 1.73 | 2.24 | 1.29 | Eh/El | 3.00 | 5.00 | 1.67 | (Eh*Wl)/(El*Wh) | 1.07 | 1.05 | 1.03 | Eh/El | 0.333 | 0.200 | 0.600 | | TENSION AND COMPRESSION | MAX. PERMISSIBLE STRESS | sqrt(fh/fl) | 1.22 | 1.41 | 1.15 | fh/fl | 1.50 | 2.00 | 1.33 | (fh*Wl)/(fl*Wh) | 0.536 | 0.461 | 0.860 | 1:1 | 1:1 | 1:1 | 1:1 | | STRESS DUE TO TEMPERATURE GRADIENT | | | | | | | | | | | | | | 2(El*CH)/(Eh*CL) | 0.200 | 0.153 | 0.750 | | BENDING - WIDTH OF BEAM CONSTANT | CONSTANT DEFLECTION | cbrt(Eh/El) | 1.44 | 1.71 | 1.18 | sqrt(Eh/El) | 1.44 | 1.71 | 1.18 | ((Eh/El)^(2/3))*(Wl/Wh) | 0.515 | 0.313 | 0.760 | (El/Eh)^(2/3) | 0.485 | 0.342 | 0.710 | | BENDING - WIDTH OF BEAM CONSTANT | MAX. PERMISSIBLE STRESS | sqrt(fh/fl) | 1.22 | 1.41 | 1.15 | fh/fl | 1.22 | 1.41 | 1.15 | (fh*Wl)/(fl*Wh) | 0.436 | 0.325 | 0.740 | 1:1 | 1:1 | 1:1 | 1:1 | | BENDING - CONSTANT FORM OF SECTION | CONSTANT DEFLECTION | 4rt(Eh/El) | 1.32 | 1.50 | 1.14 | sqrt(Eh/El) | 1.73 | 2.24 | 1.29 | (Eh*Wl)/(El*Wh) | 0.620 | 0.517 | 0.832 | 4rt((El/Eh)^3) | 0.440 | 0.300 | 0.685 | | BENDING - CONSTANT FORM OF SECTION | MAX. PERMISSIBLE STRESS | cbrt(fh/fl) | 1.15 | 1.26 | 1.09 | (fh/fl)^(2/3) | 1.31 | 1.59 | 1.21 | ((fh/fl)^(2/3))*(Wl/Wh) | 0.468 | 0.366 | 0.780 | 1:1 | 1:1 | 1:1 | 1:1 | | SLENDER COLUMNS | MAX PERMISSIBLE STRESS | sqrt((Eh*fl)/(El*fh)) | 1.42 | 1.58 | 1.12 | (Eh*fl)/(El*fh) | 2.00 | 2.50 | 1.25 | Wl/Wh | 0.720 | 0.576 | 0.807 | 1:1 | 1:1 | 1:1 | 1:1 | | TORSION | CONSTANT ANGLE OF DEFLECTION | 4rt(Th/Tl) | 1.32 | 1.50 | 1.14 | sqrt(Th/Tl) | 1.73 | 2.24 | 1.29 | (Th*Wl)/(Tl*Wh) | 0.620 | 0.517 | 0.832 | 4rt((Tl/Th)^3) | 0.440 | 0.300 | 0.685 | | BENDING VIBRATIONS CONST. FORM OF SECTION | CONST. FREQUENCY OF FREE VIBRATION | 4rt(Eh/El) | 1.32 | 1.50 | 1.14 | sqrt(Eh/El) | 1.73 | 2.24 | 1.29 | (Eh*Wl)/(El*Wh) | 0.620 | 0.517 | 0.832 | cbrt(El/Eh) | 0.440 | 0.300 | 0.685 | E = YOUNGS MODULUS, T = TORSION MODULUS, f = MAX PERMISSIBLE STRESS, W = DENSITY, a = COEFFICIENT OF LINEAR EXPANSION. C = COEFFICIENT OF THERMAL CONDUCTIVITY. H = HEAVY, L = LIGHT. DATA SUMMARISED FROM "BASES OF DESIGN IN LIGHT ALLOYS" IN "LIGHT METALS" OF JULY 1939. ROLLS-ROYCE LTD. PRINT F.O.C. 8 MAR 1940 DERBY. | ||