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17.5:

Stress on an Oblique Plane

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Mechanical Engineering
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JoVE 核 Mechanical Engineering
Stress on an Oblique Plane

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Consider a member subjected to axial forces. Introduce a sectional plane inclined to the normal plane, called an oblique plane. The stresses acting on this oblique plane can be resolved into two components: normal and tangential to the section. The normal component represents the resultant of normal forces distributed over the section, while the tangential component represents the resultant of shearing forces. The average normal and shearing stresses can be calculated by dividing the normal and tangential forces by the area of the section. The normal stress is maximum when the plane of the section is perpendicular to the axis of the member and approaches zero when the sectional plane is parallel to the axis. The shearing stress is maximum when the sectional plane is inclined at 45 degrees and approaches zero when the sectional plane is parallel or perpendicular to the axis of the member. Depending on the orientation of the plane, the same load can produce either a normal stress with no shearing stress or both normal and shearing stresses of equal magnitude.

17.5:

Stress on an Oblique Plane

Understanding stress on an oblique plane under axial loading is pivotal in material mechanics. This analysis offers insight into a material's durability and strength, which is crucial for civil engineering and structural design. Axial loading refers to force application along the material's central axis, causing compression or elongation and leading to normal stress. Normal stress occurs when a force acts perpendicularly to the material's area, resulting in compressive or tensile stress. When the stress plane isn't perpendicular to the load, it's an oblique plane, and the stress state includes both normal and shearing stress. Shearing stress happens when the force acts parallel to the area, deforming the material shape without volume change.

Considering a two-force member subject to axial force P and examining a section at an angle θ to the normal plane, the stresses on this oblique plane can be divided into normal (F) and tangential (V) components. Dividing F and V by the section's area provides the average normal and shearing stresses. The plane's orientation significantly impacts the material's stress state. Depending on the plane's orientation, the same load can induce only normal stress or both normal and shearing stresses of equal magnitude. Such understanding is crucial for designing robust, efficient structures.