The above meaning and definition are indicative and should be verified by other sources that are not used for medical and legal purposes. The connection details of these structures may be more susceptible to strength issues (than stiffness issues) due to the effects of increased stress. Note that the final strength of a beam during bending depends on the final strength of its material and cross-sectional modulus, not its stiffness and second surface moment. However, its deviation and therefore its resistance to Euler buckling depends on these last two values. Eg. For two bodies having the same mass under the bending and torsional state with the same modulus of elasticity E but different densities, the specific stiffness of the lighter material is higher than that of the heavier material because the plate thickness or shaft diameter of a lighter material is greater than that of the heavier material. To emphasize this point, consider the question of choosing a material for the construction of an aircraft. 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 compromising (tensile strength). The problem with this idea is that there would be a significant sacrifice of rigidity, so that the wings, for example, could bend unacceptably. Since it is stiffness, not tensile strength, that determines this type of decision for aircraft, let`s say they are controlled by stiffness.
The advantage of a specific module is to find materials that produce structures with minimal weight when the primary design stress is physical deflection or deformation rather than the load at fracture – this is also called the “stiffness-driven” structure. Many common structures are driven by rigidity for much of their use, such as airplane wings, bridges, masts, and bicycle frames. Using specific stiffness in traction applications is simple. The stress stiffness and total mass for a given length are directly proportional to the cross section. Therefore, the power of a beam in voltage depends on the modulus of elasticity divided by the density. However, caution should be exercised when using this measure. Thin wall beams are ultimately limited by local buckling and torsional lateral bending. These buckling modes depend on material properties other than stiffness and density, so the density stiffness cube metric is at best a starting point for analysis. For example, most types of wood work better than most metals of this measure, but many metals can be molded into useful beams with much thinner walls than what could be achieved with wood, as wood is more susceptible to local buckling. The performance of thin-walled beams can also be significantly impaired by relatively small geometry variations such as flanges and stiffeners.
[1] [2] [3] On the other hand, when the weight of a beam is fixed, its transverse dimensions are not constrained and increasing stiffness is the main objective, the performance of the beam depends on the modulus of elasticity divided by the density squared or cube. Indeed, the total rigidity of a beam and therefore its resistance to Euler buckling under axial load and to deflection at the moment of bending is directly proportional to both the modulus of elasticity of the supporting material and the second surface moment (moment of inertia) of the beam. Specific stiffness can be used in the design of beams with Euler bending or buckling, as bending and buckling are driven by stiffness. However, the role that density plays changes depending on the boundaries of the problem. If we examine the formulas for the moment of surface inertia, we can see that the stiffness of this beam varies approximately as the fourth power of the radius. The specific modulus of elasticity is a material property composed of the modulus of elasticity by mass density of a material. It is also known as stiffness to weight ratio or specific stiffness. High specific modulus materials are widely used in aerospace applications where minimal structural weight is required.
Dimensional analysis gives units of distance to the square per time squared. The equation can be written as follows: The ratio of modulus of elasticity to density for a material. Specific modulus should not be confused with specific force, a term that compares strength to density. By combining the area and density formulas, we can see that the radius of this radius varies approximately with the opposite of the square of the density for a given mass. If you are the author of the above text and do not agree to share your knowledge for teaching, research, science (for fair use as stated in the US), please email us and we will delete your text promptly. Comparing the list of surface inertia moments with the surface formulas gives the corresponding relationship for beams of different configurations. Thus, if the transverse dimensions of a beam are limited and weight reduction is the main goal, the performance of the beam depends on the modulus of elasticity divided by the density.
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