Specific modulus

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Specific modulus is a materials property consisting of the elastic modulus per mass density of a material. It is also known as the stiffness to weight ratio or specific stiffness. High specific modulus materials find wide application in aerospace applications where minimum structural weight is required. The dimensional analysis yields units of distance squared per time squared. The equation can be written as:

Contents

where is the elastic modulus and is the density.

The utility of specific modulus is to find materials which will produce structures with minimum weight, when the primary design limitation is deflection or physical deformation, rather than load at breaking—this is also known as a "stiffness-driven" structure. Many common structures are stiffness-driven over much of their use, such as airplane wings, bridges, masts, and bicycle frames.

To emphasize the point, consider the issue of choosing a material for building an airplane. Aluminum seems obvious because it is "lighter" than steel, but steel is stronger than aluminum, so one could imagine using thinner steel components to save weight without sacrificing (tensile) strength. The problem with this idea is that there would be a significant sacrifice of stiffness, allowing, e.g., wings to flex unacceptably. Because it is stiffness, not tensile strength, that drives this kind of decision for airplanes, we say that they are stiffness-driven.

The connection details of such structures may be more sensitive to strength (rather than stiffness) issues due to effects of stress risers.

Specific modulus is not to be confused with specific strength, a term that compares strength to density.

Applications

Specific stiffness in tension

The use of specific stiffness in tension applications is straightforward. Both stiffness in tension and total mass for a given length are directly proportional to cross-sectional area. Thus performance of a beam in tension will depend on Young's modulus divided by density .

Specific stiffness in buckling and bending

Specific stiffness can be used in the design of beams subject to bending or Euler buckling, since bending and buckling are stiffness-driven. However, the role that density plays changes depending on the problem's constraints.

Beam with fixed dimensions; goal is weight reduction

Examining the formulas for buckling and deflection, we see that the force required to achieve a given deflection or to achieve buckling depends directly on Young's modulus.

Examining the density formula, we see that the mass of a beam depends directly on the density.

Thus if a beam's cross-sectional dimensions are constrained and weight reduction is the primary goal, performance of the beam will depend on Young's modulus divided by density .

Beam with fixed weight; goal is increased stiffness

By contrast, if a beam's weight is fixed, its cross-sectional dimensions are unconstrained, and increased stiffness is the primary goal, the performance of the beam will depend on Young's modulus divided by either density squared or cubed. This is because a beam's overall stiffness, and thus its resistance to Euler buckling when subjected to an axial load and to deflection when subjected to a bending moment, is directly proportional to both the Young's modulus of the beam's material and the second moment of area (area moment of inertia) of the beam.

Comparing the list of area moments of inertia with formulas for area gives the appropriate relationship for beams of various configurations.

Beam's cross-sectional area increases in two dimensions

Consider a beam whose cross-sectional area increases in two dimensions, e.g. a solid round beam or a solid square beam.

By combining the area and density formulas, we can see that the radius of this beam will vary with approximately the inverse of the square of the density for a given mass.

By examining the formulas for area moment of inertia, we can see that the stiffness of this beam will vary approximately as the fourth power of the radius.

Thus the second moment of area will vary approximately as the inverse of the density squared, and performance of the beam will depend on Young's modulus divided by density squared.

Beam's cross-sectional area increases in one dimension

Consider a beam whose cross-sectional area increases in one dimension, e.g. a thin-walled round beam or a rectangular beam whose height but not width is varied.

By combining the area and density formulas, we can see that the radius or height of this beam will vary with approximately the inverse of the density for a given mass.

By examining the formulas for area moment of inertia, we can see that the stiffness of this beam will vary approximately as the third power of the radius or height.

Thus the second moment of area will vary approximately as the inverse of the cube of the density, and performance of the beam will depend on Young's modulus divided by density cubed.

However, caution must be exercised in using this metric. Thin-walled beams are ultimately limited by local buckling and lateral-torsional buckling. These buckling modes depend on material properties other than stiffness and density, so the stiffness-over-density-cubed metric is at best a starting point for analysis. For example, most wood species score better than most metals on this metric, but many metals can be formed into useful beams with much thinner walls than could be achieved with wood, given wood's greater vulnerability to local buckling. The performance of thin-walled beams can also be greatly modified by relatively minor variations in geometry such as flanges and stiffeners. [1] [2] [3]

Stiffness versus strength in bending

Note that the ultimate strength of a beam in bending depends on the ultimate strength of its material and its section modulus, not its stiffness and second moment of area. Its deflection, however, and thus its resistance to Euler buckling, will depend on these two latter values.

Approximate specific stiffness for various materials

Specific stiffness of the full range of materials Specific stiffness of materials.svg
Specific stiffness of the full range of materials
Specific stiffness of materials within the range 0.9-5.0 g/cm density and 10-1300 GPa stiffness Specific stiffness of materials detail view.svg
Specific stiffness of materials within the range 0.9–5.0 g/cm density and 10–1300 GPa stiffness
Approximate specific stiffness for various materials. No attempt is made to correct for materials whose stiffness varies with their density.
Material Young's modulus (GPa) Density (g/cm3)Young's modulus per density; specific stiffness (106 m2s−2)Young's modulus per density squared (103 m5kg−1s−2)Young's modulus per density cubed (m8kg−2s−2)Reference
Latex foam, low density, 10% compression [4] 5.9×10^−70.069.83×10^−60.0001640.00273
Reversible Assembled Cellular Composite Materials0.01230.00721.7123732,953 [5] [6]
Self Reprogrammable Mechanical Metamaterials0.00111290.01030.10810.51,018 [7] [8]
Latex foam, low density, 40% compression [4] 1.8×10^−60.063×10^−50.00050.00833
Latex foam, high density, 10% compression [4] 1.3×10^−50.26.5×10^−50.0003250.00162
Latex foam, high density, 40% compression [4] 3.8×10^−50.20.000190.000950.00475
Silica aerogel, medium density [9] 0.000350.090.003890.04320.48
Rubber (small strain)0.055±0.0451.055±0.145 [10] 0.059±0.0510.06345±0.056550.0679±0.0621
Expanded polystrene (EPS) foam, low density (1 lb/ft3) [11] 0.001370.0160.0865.35334
Silica aerogel, high density [9] 0.0240.250.0960.3841.54
Expanded polystrene (EPS) foam, medium density (3 lb/ft3) [11] 0.005240.0480.112.347
Low-density polyethylene 0.20.925±0.0150.215±0.0050.235±0.0050.255±0.015
PTFE (Teflon)0.52.20.230.100.047
Duocel aluminum foam, 8% density [12] 0.1020.2160.4722.1910.1
Extruded polystrene (XPS) foam, medium density (Foamular 400) [13] [14] 0.0137890.02890.4816.5571
Extruded polystrene (XPS) foam, high density (Foamular 1000) [13] [14] 0.025510.04810.5311229
HDPE 0.80.95 [15] 0.840.890.93
Duocel copper foam, 8% density [16] 0.7360.7171.031.432
Polypropylene [17] 1.2±0.30.91.33±0.331.48±0.371.65±0.41
Polyethylene terephthalate 2.35±0.351.4125±0.04251.7±0.31.17±0.230.875±0.225
Nylon 3.0±1.01.152.6±0.92.25±0.751.95±0.65
Polystyrene 3.25±0.251.053.1±0.22.95±0.252.8±0.2
Biaxially-oriented Polypropylene [17] 3.2±1.00.93.56±1.113.95±1.234.39±1.37
Medium-density fibreboard 40.75 [18] 5.37.19.5
Titanium foam, low density [19] 5.30.9915.355.45.45
Titanium foam, high density [19] 203.156.352.020.64
Foam glass [20] 0.90.127.562.5521
Copper (Cu)1178.94131.50.16
Brass and bronze 112.5±12.58.565±0.16513.0±2.01.55±0.250.18±0.03
Zinc (Zn)1087.14152.10.29
Oak wood (along grain)110.76±0.17 [21] 15.5±3.522.5±9.534.0±20.0
Concrete (under compression)40±102.417±46.95±1.752.9±0.7
Glass-reinforced plastic [22] [23] [24] 31.65±14.451.818±89.65±4.355.4±2.5
Pine wood 8.9630.505±0.155 [21] 20±647±26120±89
Balsa, low density (4.4 lb/ft3) [25] 1.410.071202803,940
Tungsten (W)40019.25211.10.056
Sitka spruce green [26] [27] [28] 8.7±0.70.3723.5±264±5172±13
Osmium (Os)55022.59241.10.048
Balsa, medium density (10 lb/ft3) [25] 3.860.16324145891
Steel 2007.9±0.1525±0.53.2±0.10.41±0.02
Titanium alloys 112.5±7.54.525±25.55±0.351.23±0.08
Balsa, high density (16 lb/ft3) [25] 6.570.2652594353
Wrought iron 200±107.7±0.226±23.35±0.350.445±0.055
Magnesium metal (Mg)451.73826158.6
Sitka spruce dry [26] [27] [28] 10.4±0.80.426±265±5162±12
Macor machineable glass-ceramic [29] 66.92.5226.5510.538.14
Cordierite [30] 702.626.910.43.98
Glass 70±202.6±0.2 [31] 28±1011.2±4.84.4±2.1
Tooth enamel (largely calcium phosphate)832.8 [32] 30113.8
E-Glass fiber [33] [34] 812.6231124.5
Molybdenum (Mo)32910.28323.10.30
Basalt fiber 892.733124.5
Zirconia [30] 2076.0434.35.670.939
Tungsten carbide (WC)550±10015.834.5±6.52.2±0.40.135±0.025
S-Glass fiber [33] [35] 892.536145.7
Flax fiber [36] [37] [38] [39] 45±341.35±0.1536.65±29.3530±2525±21
single-crystal Yttrium iron garnet (YIG)2005.17 [40] 397.51.4
Kevlar 29 [41] (tensile only [42] )70.51.44493424
Steatite L-5 [30] 1382.7150.918.86.93
Mullite [30] 1502.853.619.16.83
Dyneema SK25 Ultra-high-molecular-weight polyethylene (tensile only) [43] 520.97545557
Beryllium, 30% porosity [44] 761.358.54534.6
Kevlar 49 [41] (tensile only [42] )112.41.44785438
Silicon [45] 1852.329793415
Alumina fiber (Al2O3) [46] [47] [35] 3003.595±0.31584±724±46.76±1.74
Syalon 501 Silicon nitride [48] 3404.0184.821.15.27
Sapphire [30] 4003.9710125.46.39
Alumina [30] 3933.810327.27.16
Carbon fiber reinforced plastic (70:30 fibre:matrix, unidirectional, along grain) [49] 1811.61137144
Dyneema SK78/Honeywell Spectra 2000 UHMWPE (tensile only) [43] [50] 121±110.97125±11128±12132±12
Silicon carbide (SiC)4503.211404414
Beryllium (Be)2871.851558445
Boron fiber [51] 4002.541576224
Boron nitride [30] 6752.2829613057
Diamond (C)1,2203.533479828
Dupont E130 carbon fiber [52] 8962.1541719490
Approximate specific stiffness for various species of wood [53]
Material Young's modulus (GPa) Density (g/cm3)Young's modulus per density; specific stiffness (106 m2s−2)Young's modulus per density squared (103 m5kg−1s−2)Young's modulus per density cubed (m8kg−2s−2)
Applewood or wild apple (Pyrus malus)8.767150.74511.76815.795921.2026
Ash, black (Fraxinus nigra)11.04230.52620.992939.910575.8755
Ash, blue (quadrangulata)9.649740.60316.002926.538844.0113
Ash, green (Fraxinus pennsylvanica lanceolata)11.47380.61018.809530.835250.5495
Ash, white (Fraxinus americana)12.24850.63819.198330.091447.1651
Aspen (Populus tremuloides)8.217970.40120.493751.1065127.448
Aspen, large tooth (Populus grandidentata)9.767420.41223.707357.5421139.665
Basswood (Tilia glabra or Tilia americanus)10.0910.39825.354463.7045160.061
Beech (Fagus grandifolia or Fagus americana)11.57180.65517.666926.972441.1793
Beech, blue (Carpinus caroliniana)7.37460.71710.285414.34520.007
Birch, gray (Betula populifolia)7.81590.55214.159225.650846.4688
Birch, paper (Betula papyrifera)10.97360.60018.289430.482350.8039
Birch, sweet (Betula lenta)14.90610.71420.876929.239440.9515
Buckeye, yellow (Aesculus octandra)8.129710.38321.226455.4214144.703
Butternut (Juglans cinerea)8.139520.40420.147349.8696123.44
Cedar, eastern red (Juniperus virginiana)6.001670.49212.198524.793750.3938
Cedar, northern white (Thuja occidentalis)5.570180.31517.683156.1368178.212
Cedar, southern white (Chamaecyparis thvoides)6.423360.35218.248251.8414147.277
Cedar, western red (Thuja plicata)8.031650.34423.347867.8715197.301
Cherry, black (Prunus serotina)10.25780.53419.209335.972467.3641
Cherry, wild red (Prunus pennsylvanica)8.747530.42520.582448.4292113.951
Chestnut (Castanea dentata)8.531790.45418.792541.393191.1743
Cottonwood, eastern (Populus deltoides)9.532060.43322.01450.8407117.415
Cypress, southern (Taxodium distichum)9.904720.48220.549242.633288.4506
Dogwood (flowering) (Cornus Florida)10.64020.79613.367116.792821.0965
Douglas fir (coast type) (Pseudotsuga taxifolia)13.30760.51225.991550.764699.1495
Douglas fir (mountain type) (Pseudotsuga taxifolia)9.620320.44621.570248.3637108.439
Ebony, Andaman marble-wood (India) (Diospyros kursii)12.45440.97812.734613.021113.314
Ebony, Ebè marbre (Mauritius, E. Africa) (Diospyros melanida)9.87530.76812.858516.742821.8005
Elm, American (Ulmus americana)9.29670.55416.781130.290754.6764
Elm, rock (Ulmus racemosa or Ulmus thomasi)10.650.65816.185424.597937.3829
Elm, slippery (Ulmus fulva or pubescens)10.2970.56818.128531.916456.1908
Eucalyptus, Karri (W. Australia) (Eucalyptus diversicolor)18.48550.82922.298626.898232.4465
Eucalyptus, Mahogany (New South Wales) (Eucalyptus hemilampra)15.76911.05814.904614.087513.3153
Eucalyptus, West Australian mahogany (Eucalyptus marginata)14.33730.78718.217723.148329.4133
Fir, balsam (Abies balsamea)8.620050.41420.821450.2932121.481
Fir, silver (Abies amabilis)10.5520.41525.426461.2684147.635
Gum, black (Nyssa sylvatica)8.227780.55214.905427.002548.9176
Gum, blue (Eucalyptus globulus)16.50460.79620.734426.048332.7239
Gum, red (Liquidambar styraciflua)10.24790.53019.335836.482668.835
Gum, tupelo (Nyssa aquatica)8.718110.52416.637631.751260.5939
Hemlock eastern (Tsuga canadensis)8.296430.43119.249244.6618103.624
Hemlock, mountain (Tsuga martensiana)7.81590.48016.283133.923270.6733
Hemlock, western (Tsuga heterophylla)9.953750.43223.041153.3359123.463
Hickory, bigleaf shagbark (Hicoria laciniosa)13.09190.80916.182820.003424.7261
Hickory, mockernut (Hicoria alba)15.39640.82018.776122.897727.9241
Hickory, pignut (Hicoria glabra)15.72010.82019.170823.37928.511
Hickory, shagbark (Hicoria ovata)14.95510.83617.888921.398225.596
Hornbeam (Ostrya virginiana)11.75820.76215.430720.250226.5751
Ironwood, black (Rhamnidium ferreum)20.5941.077−1.3017.48±1.6414.97±2.7812.93±3.56
Larch, western (Larix occidentalis)11.65030.58719.847233.811257.6
Locust, black or yellow (Robinia pseudacacia)14.20.70820.056528.328440.0119
Locust honey (Gleditsia triacanthos)11.42470.66617.154325.757238.6744
Magnolia, cucumber (Magnolia acuminata)12.51330.51624.250646.997291.0798
Mahogany (W. Africa) (Khaya ivorensis)10.58140.66815.840423.713135.4987
Mahogany (E. India) (Swietenia macrophylla)8.012030.5414.837127.476150.8817
Mahogany (E. India) (Swietenia mahogani)8.727920.5416.162829.931155.428
Maple, black (Acer nigrum)11.18940.62018.047429.108746.9495
Maple, red (Acer rubrum)11.32670.54620.744837.994269.5865
Maple, silver (Acer saccharinum)7.894350.50615.601530.83360.9347
Maple, sugar (Acer saccharum)12.65060.67618.713927.683240.9515
Oak, black (Quercus velutina)11.30710.66916.901425.263737.7634
Oak, bur (Quercus macrocarpa)7.090210.67110.566615.747623.4688
Oak, canyon live (Quercus chrysolepis)11.26780.83813.446116.045519.1473
Oak, laurel (Quercus Montana)10.92460.67416.208624.048435.6801
Oak, live (Quercus virginiana)13.5430.97713.861814.188114.5221
Oak, post (Quercus stellata or Quercus minor)10.42450.73814.125319.1425.9349
Oak, red (Quercus borealis)12.49370.65719.016228.944144.0549
Oak, swamp chestnut (Quercus Montana (Quercus prinus))12.22890.75616.175821.396528.3023
Oak swamp white (Quercus bicolor or Quercus platanoides)14.18040.79217.904622.606828.5439
Oak, white (Quercus alba)12.26810.71017.27924.336734.277
Paulownia (P. tomentosa)6.8940.27425.160691.8269335.134
Persimmon (Diospyros virginiana)14.1510.77618.235823.499830.2832
Pine, eastern white (Pinus strobus)8.806370.37323.609663.2964169.696
Pine, jack (Pinus banksiana or Pinus divericata)8.512170.46118.464640.053386.8836
Pine, loblolly (Pinus taeda)13.27820.59322.391637.759863.6759
Pine, longleaf (Pinus palustris)14.17060.63822.21134.813554.5665
Pine, pitch (Pinus rigida)9.463420.54217.460232.214459.4361
Pine, red (Pinus resinosa)12.39560.50724.448948.222795.1139
Pine, shortleaf (Pinus echinata)13.18990.58422.585538.673866.2223
Poplar, balsam (Populus balsamifera or Populus candicans)7.021560.33121.213264.0881193.62
Poplar, yellow (Liriodendron tulipifera)10.37540.42724.298456.905133.267
Redwood (Sequoia sempervirens)9.394770.43621.547649.4212113.351
Sassafras (Sassafras uariafolium)7.747250.47316.37934.627873.209
Satinwood (Ceylon) (Chloroxylon swietenia)10.79711.03110.472510.15769.85217
Sourwood (Oxydendrum arboreum)10.62060.59317.9130.202350.9313
Spruce, black (Picea mariana)10.48330.42824.493757.2283133.711
Spruce, red (Picea rubra or Picea rubens)10.50290.41325.430861.5758149.094
Spruce, white (Picea glauca)9.816460.43122.77652.8446122.609
Sycamore (Platanus occidentalis)9.826260.53918.230533.822962.7512
Tamarack (Larix laricina or Larix americana)11.31690.55820.281136.346165.1364
Teak (India) (Tectona grandis)11.71890.589219.889633.756957.2928
Walnut, black (Juglans nigra)11.62090.56220.677736.793165.4682
Willow, black (Salix nigra)5.030810.40812.330430.221674.0726
Specific stiffness of the elements [54] [55]
Material Young's modulus (GPa) Density (g/cm3)Young's modulus per density; specific stiffness (106 m2s−2)Young's modulus per density squared (103 m5kg−1s−2)Young's modulus per density cubed (m8kg−2s−2)
Thallium 811.80.6750.0570.00481
Cesium 1.71.880.9050.4810.256
Arsenic 85.731.40.2440.0426
Lead 1611.31.410.1240.011
Indium 117.311.50.2060.0282
Rubidium 2.41.531.571.020.667
Selenium 104.822.080.4310.0894
Bismuth 329.783.270.3350.0342
Europium 185.243.430.6550.125
Ytterbium 246.573.650.5560.0846
Barium 133.513.71.060.301
Gold 7819.34.040.2090.0108
Plutonium 9619.84.840.2440.0123
Cerium 346.695.080.760.114
Praseodymium 376.645.570.8390.126
Cadmium 508.655.780.6680.0773
Neodymium 417.015.850.8340.119
Hafnium 7813.35.860.440.0331
Lanthanum 376.156.020.980.159
Promethium 467.266.330.8720.12
Thorium 7911.76.740.5750.049
Samarium 507.356.80.9250.126
Lutetium 679.846.810.6920.0703
Terbium 568.226.810.8290.101
Tin 507.316.840.9360.128
Tellurium 436.246.891.10.177
Gadolinium 557.96.960.8810.112
Dysprosium 618.557.130.8340.0976
Holmium 648.797.280.8270.0941
Erbium 709.077.720.8520.0939
Platinum 16821.47.830.3650.017
Thulium 749.327.940.8520.0914
Silver 8510.58.10.7720.0736
Antimony 556.78.211.230.183
Lithium 4.90.5359.1617.132
Palladium 1211210.10.8370.0696
Zirconium 676.5110.31.580.243
Sodium 100.96810.310.711
Uranium 20819.110.90.5730.0301
Tantalum 18616.611.20.6710.0403
Niobium 1058.5712.31.430.167
Calcium 201.5512.98.325.37
Yttrium 644.4714.33.20.716
Copper 1308.9614.51.620.181
Zinc 1087.1415.12.120.297
Silicon 472.3320.28.663.72
Vanadium 1286.1120.93.430.561
Tungsten 41119.221.41.110.0576
Rhenium 46321221.050.0499
Rhodium 27512.422.11.770.143
Nickel 2008.9122.52.520.283
Iridium 52822.623.41.040.046
Cobalt 2098.923.52.640.296
Scandium 742.9824.88.312.78
Titanium 1164.5125.75.711.27
Magnesium 451.7425.914.98.57
Aluminum 702.725.99.63.56
Manganese 1987.4726.53.550.475
Iron 2117.8726.83.40.432
Molybdenum 32910.3323.110.303
Ruthenium 44712.436.12.920.236
Chromium 2797.1938.85.40.751
Beryllium 2871.851558445.5

See also

Related Research Articles

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Flexural rigidity is defined as the force couple required to bend a fixed non-rigid structure by one unit of curvature, or as the resistance offered by a structure while undergoing bending.

<span class="mw-page-title-main">I-beam</span> Construction element

An I-beam is any of various structural members with an I or H-shaped cross-section. Technical terms for similar items include H-beam, w-beam, universal beam (UB), rolled steel joist (RSJ), or double-T. I-beams are typically made of structural steel and serve a wide variety of construction uses.

The second polar moment of area, also known as "polar moment of inertia" or even "moment of inertia", is a quantity used to describe resistance to torsional deformation (deflection), in objects with an invariant cross-section and no significant warping or out-of-plane deformation. It is a constituent of the second moment of area, linked through the perpendicular axis theorem. Where the planar second moment of area describes an object's resistance to deflection (bending) when subjected to a force applied to a plane parallel to the central axis, the polar second moment of area describes an object's resistance to deflection when subjected to a moment applied in a plane perpendicular to the object's central axis. Similar to planar second moment of area calculations, the polar second moment of area is often denoted as . While several engineering textbooks and academic publications also denote it as or , this designation should be given careful attention so that it does not become confused with the torsion constant, , used for non-cylindrical objects.

<span class="mw-page-title-main">Torsion constant</span> Geometrical property of a bars cross-section

The torsion constant or torsion coefficient is a geometrical property of a bar's cross-section. It is involved in the relationship between angle of twist and applied torque along the axis of the bar, for a homogeneous linear elastic bar. The torsion constant, together with material properties and length, describes a bar's torsional stiffness. The SI unit for torsion constant is m4.

<span class="mw-page-title-main">Sandwich-structured composite</span> Material composed of two thin, stiff skins around a lightweight core

In materials science, a sandwich-structured composite is a special class of composite materials that is fabricated by attaching two thin-but-stiff skins to a lightweight-but-thick core. The core material is normally of low strength, but its greater thickness provides the sandwich composite with high bending stiffness with overall low density.

This is an alphabetical list of articles pertaining specifically to structural engineering. For a broad overview of engineering, please see List of engineering topics. For biographies please see List of engineers.

Tonewood refers to specific wood varieties used for woodwind or acoustic stringed instruments. The word implies that certain species exhibit qualities that enhance acoustic properties of the instruments, but other properties of the wood such as esthetics and availability have always been considered in the selection of wood for musical instruments. According to Mottola's Cyclopedic Dictionary of Lutherie Terms, tonewood is:

Wood that is used to make stringed musical instruments. The term is often used to indicate wood species that are suitable for stringed musical instruments and, by exclusion, those that are not. But the list of species generally considered to be tonewoods changes constantly and has changed constantly throughout history.

Material selection is a step in the process of designing any physical object. In the context of product design, the main goal of material selection is to minimize cost while meeting product performance goals. Systematic selection of the best material for a given application begins with properties and costs of candidate materials. Material selection is often benefited by the use of material index or performance index relevant to the desired material properties. For example, a thermal blanket must have poor thermal conductivity in order to minimize heat transfer for a given temperature difference. It is essential that a designer should have a thorough knowledge of the properties of the materials and their behavior under working conditions. Some of the important characteristics of materials are : strength, durability, flexibility, weight, resistance to heat and corrosion, ability to cast, welded or hardened, machinability, electrical conductivity, etc. In contemporary design, sustainability is a key consideration in material selection. Growing environmental consciousness prompts professionals to prioritize factors such as ecological impact, recyclability, and life cycle analysis in their decision-making process.

<span class="mw-page-title-main">Filler (materials)</span> Particles added to improve its properties

Filler materials are particles added to resin or binders that can improve specific properties, make the product cheaper, or a mixture of both. The two largest segments for filler material use is elastomers and plastics. Worldwide, more than 53 million tons of fillers are used every year in application areas such as paper, plastics, rubber, paints, coatings, adhesives, and sealants. As such, fillers, produced by more than 700 companies, rank among the world's major raw materials and are contained in a variety of goods for daily consumer needs. The top filler materials used are ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), kaolin, talc, and carbon black. Filler materials can affect the tensile strength, toughness, heat resistance, color, clarity, etc. A good example of this is the addition of talc to polypropylene. Most of the filler materials used in plastics are mineral or glass based filler materials. Particulates and fibers are the main subgroups of filler materials. Particulates are small particles of filler that are mixed in the matrix where size and aspect ratio are important. Fibers are small circular strands that can be very long and have very high aspect ratios.

Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members. Other geometric properties used in design include area for tension and shear, radius of gyration for compression, and second moment of area and polar second moment of area for stiffness. Any relationship between these properties is highly dependent on the shape in question. Equations for the section moduli of common shapes are given below. There are two types of section moduli, the elastic section modulus and the plastic section modulus. The section moduli of different profiles can also be found as numerical values for common profiles in tables listing properties of such.

Electron-beam processing or electron irradiation (EBI) is a process that involves using electrons, usually of high energy, to treat an object for a variety of purposes. This may take place under elevated temperatures and nitrogen atmosphere. Possible uses for electron irradiation include sterilization, alteration of gemstone colors, and cross-linking of polymers.

<span class="mw-page-title-main">Deflection (engineering)</span> Degree to which part of a structural element is displaced under a given load

In structural engineering, deflection is the degree to which a part of a long structural element is deformed laterally under a load. It may be quantified in terms of an angle or a distance . A longitudinal deformation is called elongation.

<span class="mw-page-title-main">Structural engineering theory</span>

Structural engineering depends upon a detailed knowledge of loads, physics and materials to understand and predict how structures support and resist self-weight and imposed loads. To apply the knowledge successfully structural engineers will need a detailed knowledge of mathematics and of relevant empirical and theoretical design codes. They will also need to know about the corrosion resistance of the materials and structures, especially when those structures are exposed to the external environment.

Reversibly assembled cellular composite materials (RCCM) are three-dimensional lattices of modular structures that can be partially disassembled to enable repairs or other modifications. Each cell incorporates structural material and a reversible interlock, allowing lattices of arbitrary size and shape. RCCM display three-dimensional symmetry derived from the geometry as linked.

The four-point flexural test provides values for the modulus of elasticity in bending , flexural stress , flexural strain and the flexural stress-strain response of the material. This test is very similar to the three-point bending flexural test. The major difference being that with the addition of a fourth bearing the portion of the beam between the two loading points is put under maximum stress, as opposed to only the material right under the central bearing in the case of three-point bending.

<span class="mw-page-title-main">Euler's critical load</span> Formula to quantify column buckling under a given load

Euler's critical load or Euler's buckling load is the compressive load at which a slender column will suddenly bend or buckle. It is given by the formula:

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