Average Young's modulus values of wood along the longitudinal axis E L obtained from bending tests are given in the following table. Average values of elastic moduli along the tangential E T and radial E R axes of wood for samples from a few species are given in the following table as ratios with elastic moduli along the longitudinal E L axis.
Since the modulus of elasticity values are determined from bending, the tabulated values given above includes an effect of shear deflection. AmesWeb Calculators Material Properties. Kind of Wood. Moisture content. Young's Modulus Modulus of Elasticity. Alder, red. Ash, white. Basswood, American. Beech, American. Birch, yellow. Cherry, black. Cottonwood, eastern. Elm, American. Elm, rock.
How to Calculate Elastic Modulus
True Hickory, shagbark. Maple, sugar. Oak, red, northern. Oak, white. Tupelo, black. Walnut, black. Cedar, northern white. Cedar, western red. Douglas-fir, coast. Douglas-fir, interior west. Douglas-fir, interior north. Douglas-fir, interior south. Fir, balsam.If you push the ends of a rubber rod toward each other, you are applying a compression force and can shorten the rod by some amount. If you pull the ends away from each other, the force is called tension, and you can stretch the rod lengthwise.
If you tug one end toward you and the other end away from you, using what is called a shear force, the rod stretches diagonally.
Modulus of Elasticity (MOE) Ratings for All Species (1000 psi)
Elastic modulus E is a measure of the stiffness of a material under compression or tension, although there is also an equivalent shear modulus.
It is a property of the material and does not depend on the shape or size of the object. A small piece of rubber has the same elastic modulus as a large piece of rubber. Here F is force, and A is the cross-sectional area where the force is applied.
When stress is applied to an object, the change in shape is called strain. Normal strain, or simply strainis dimensionless. Most materials can sustain some amount of elastic deformation, although it may be tiny in a tough metal like steel. If the stress is too large, however, a material will undergo plastic deformation and permanently change shape.
Stress can even increase to the point where a material breaks, such as when you pull a rubber band until it snaps in two. The modulus of elasticity equation is used only under conditions of elastic deformation from compression or tension. For most materials, elastic modulus is so large that it is normally expressed as megapascals MPa or gigapascals GPa.
To test the strength of materials, an instrument pulls on the ends of a sample with greater and greater force and measures the resulting change in length, sometimes until the sample breaks. Elastic deformation occurs at low strains and is proportional to stress.
On a stress-strain curve, this behavior is visible as a straight-line region for strains less than about 1 percent. So 1 percent is the elastic limit or the limit of reversible deformation. Lee is a writer, electronics engineer and owner of a small high-tech company.
He also produces web content and marketing materials, and has taught physics for students taking the Medical College Admissions Test. In addition, he has written numerous scripts for engineering and physics videos for JoVE, the Journal of Visualized Experiments.
About the Author. Copyright Leaf Group Ltd.In our last post we have discussed on Elasticity and Plasticity. On the way we will learn two more terms: stress and strain. Lets get some idea about those. Let a force is applied on a body which can modify the shape and size of the object. Here F is the action and F1 is the reaction force. The restoring force per unit area is called stress.
A solid may change its dimensions is 3 different ways, resulting in 3 types of Stress and strain. Tensile and Compressive stress also cumulatively known as Longitudinal stress.
Here forces are applied at right angle to the cross sectional area or surfaces to either elongate or compress the object. That means these forces tend to cause change in length of the solid body and generates Longitudinal Stress. As said this stress may be of 2 types, tensile and compressive. Tensile stress tends to enhance length and compressive stress tries to decrease the length. Longitudinal Strain: Say the original length is L and change in length is l. Here comes the term Longitudinal Strain which is stated as the change in length per unit length.
If 2 equal and opposite deforming forces are applied parallel to the cross sectional area of a cylinder like object, then there is a relative displacement between the opposite faces of the cylinder. In this case, the restoring force per unit area due to the applied tangential force is called tangential or shearing stress. In the diagram, 2 equal, opposite and parallel forces with magnitude F cause a relative displacement x between the opposite faces of the cylinder.
When a solid say sphere is placed in fluid under high pressure and compressed uniformly on all sides, then the force applied by the fluid acts in perpendicular direction at each point of the surface. This is called Hydraulic Compression. This leads to decrease in volume. The internal restoring force per unit area is called Hydraulic Stress.
Related strain is called volume strain which is the ratio of change in volume and initial volume. This K is a proportionality constant called Modulus of Elasticity. Now considering 3 different types of stress for solid, we have 3 different sets of elasticity modulus.
Please note that Strain is dimensionless. This is also known as Modulus of Rigidity. Here P is the pressure. Skip to content. By Anupam M.Design values provided herein are for Western softwood species manufactured and shipped by mills in the 12 contiguous Western states and Alaska.
Except as otherwise noted, the values are computed in accordance with ASTM standards based on clear-wood tests or on tests of full-size pieces in specific grades. The ASTM methods result in stiffness E values that are expected to be an average for the grades listed, while compression perpendicular-to-grain Fc values are mean-based.
Standard ASTM reductions have been made to values to account for safety and duration of load. Lumber strength properties are assigned to five basic properties: fiber stress in bending Fbtension parallel-to-grain Fthorizontal shear Fvcompression parallel-to-grain Fcand compression perpendicular-to-grain Fc.
The modulus of elasticity E measures the amount a piece of lumber will deform in proportion to an applied load under elastic range stresses. It is a measure of stiffness and not a strength property. When loads are applied, structural members bend, producing tension in the fibers along the faces farthest from the applied load and compression in the fibers along the face nearest to the applied load. These induced stresses in the fibers are designated as "extreme fiber stress in bending" Fb.
Single Member Fb design values are used in design where the strength of an individual piece, such as a beam, may be solely responsible for carrying a specific design load. Repetitive Member Fb design values are used in design when three or more load-sharing members, such as joists, rafters, or studs, are spaced no more than 24" apart and are joined by flooring, sheathing, or other load-distributing elements.
Repetitive members are also used where pieces are adjacent, such as decking. The lumber must be of the same size, species and grade or higher to qualify as a repetitive member. Fiber Stress in Tension - Ft Fig. Tensile stresses are similar to compression parallel to grain in that they act across the full cross section and tend to stretch the piece. Length does not affect tensile stresses.
Horizontal Shear - Fv Fig. Horizontal shear stresses tend to slide fibers over each other horizontally and are most predominant in short, heavily-loaded deep beams.
Increasing beam cross section decreases shear stresses. Compression Perpendicular-to-Grain - Fc Fig. Where a joist, beam, or similar piece of lumber bears on supports, the loads tend to compress the fibers. It is therefore necessary the bearing area is sufficient to prevent side-grain crushing.
Compression Parallel-to-Grain - Fc Fig. In many parts of a structure, stress grades are used where the loads are supported on the ends of the pieces. Such uses are as studs, posts, columns, and struts. The internal stress induced by this kind of loading is the same across the whole cross section and the fibers are uniformly stressed parallel to, and along the full length of, the piece. Modulus of Elasticity - E Fig. The modulus of elasticity E is a ratio of the amount a material will deflect in proportion to an applied load.
Any special adjustments follow the appropriate tables of design values. Allowable design values for wood members and connections in particular end uses shall be appropriate for the conditions in which the member is used, taking into account the differences in wood strength properties given the conditions of use.
Lumber Mechanical Properties Figures Lumber Design Values and Framing Spans.
All Design Value Related Publications. Western Wood Products Association represents softwood lumber manufacturers in the 12 Western states and Alaska.
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Mechanical Engineering. What is the modulus of elasticity of timber? Wiki User It depends on the timber type. A typical range is 1, psi 6.
Liquids are isotropic and therefore do not have a modulus of elasticity. Asked in Mechanical Engineering What are the different types of modulus of elasticity? Asked in Mechanical Engineering, Civil Engineering What is the significance of modulus of elasticity? Asked in Physics, Civil Engineering What is the difference between young's modulus and dynamic modulus of elasticity?
Young's Modulus modulus of elasticity describes the stress-strain behavior of a material under monotonic loading.
The dynamic modulus of elasticity describes the same behavior under cyclic or vibratory loading. Modulus of elasticity will be 2. Asked in Physics, Mechanical Engineering What is the dimension of youngs modulus of elasticity?
Asked in Physics, Engineering, Mechanical Engineering Formula for bulk modulus of volume of elasticity? Asked in Mechanical Engineering What are the different types of modulus elasticity? Asked in Mechanical Engineering What is the difference between Youngs modulus and the modulus of elasticity?Identifying and Using Hundreds of Woods Worldwide. It contains many of the most popular articles found on this website, as well as hundreds of wood profiles—laid out with the same clarity and convenience of the website—packaged in a shop-friendly hardcover book.
From your diagram, it appears you are actually talking about the flexural modulus, which may or may not be equivalent to the tensile modulus or the compressive modulus, depending on the material. Perhaps you do? For example, a quater-sawn guitar neck is much stiffer then one made from plain-sawn wood.
As we all know, Wood is anisotropic, therefore strength is highly dependent on relative direction of the grain. Use MOE with caution and keep in mind that Wood is stronger along the grain than across it. Vastly more resources would need to be put into wood research in order to make a moderately accurate information data base of wood rigidity among the many variables found in nature.
I go with generalities and overdesign. The thing that folks miss here is that in using Youngs modulus with say metals the general assumption is that it is the same in tensile stress as in compressive stress. With wood this is definitely not the case.
So in a wooden beam under load the modulus on the tension side of the beam is not the same as in the compression side. Hence difficult to analyse. There are at least 2 reasons there are different published values for E for the same named wood and neither has to do with compression or tension of the wood fibers.
The Modulus of Elasticity published in many texts in the past was based on bending tests instead of opposing shear forces used in modern testing procedures. The short answer is that I use the average of as many credible sources of data that I can find, and when this article was written, I was quoting from only one source, while the page on red oak has since been updated to reflect the most recent averaged data.
Those are good values to use. Woods actually vary a lot more than that. It is not like you are testing a mill run of SAE steel, or something.
Wood varies in the same species by geographical location. It also varies by altitude in the same location. Scots pines at sea level to feet are soft and weak.
Actually, it is a discrepancy. Perhaps you meant to say it is not a large difference. If so, I would agree with that. But it is most definitely a discrepancy in the database.
Even 1. A reference should not give different values for the same thing. Now, if the reference had quoted a range the same range both timesthat would be fine. But giving two different numbers for the same thing is a discrepancy. Hang a weight from steel wire; say 1 pound. This weight acts under gravity to deform this wire along its length. The force is pure Tensile Force. It can be clearly seen in the above woods database diagram, that a system of compression and tension is happening.
The true lengthwise deformation would be given by Pythagoras. Awesome information and nice with everyone sharing comments trying to explain the modulus of elasticity.
It makes it possible to read different explanations. This page is and will help me through my woodscience course. MOE is the ration between the stress and the non-dimensional relative elongation.