Name: normal stress in axial loading
Uploaded: 2024-03-07T13:22:32.000Z
Duration: 1 min 19 s
Channel: JoVE

軸方向の力を受けるロッドを考えてみましょう。その結果、断面積全体に抵抗力が発生し、これを応力と呼びます。応力のSI単位はニュートン/平方メートルです。
次に、軸方向の力を受ける橋梁トラス部材について考えてみます。これは、垂直応力と呼ばれる、断面に垂直な内力と応力を発生させます。
結果として得られる垂直応力は、特定の点ではなく、断面上の平均応力を表します。
平衡の条件によれば、内力は加えられた力と等しくなり、応力分布は適用点の近くを除いて均一であることを意味します。
ただし、この一様分布は、荷重の作用線が断面の重心を通過する場合にのみ可能であり、中心荷重と呼ばれます。
軸荷重が偏心して適用されると、モーメントが追加されるため、力と応力の分布を均一または対称にすることはできません。
したがって、軸方向に荷重がかかったメンバーの実際の応力分布は静的に不確定であり、荷重適用の特定のモードによって異なります。

垂直応力

垂直応力は、力が材料の断面積に対して垂直または垂直に作用するときに発生する応力の一種です。 この応力は、物体の軸に沿って力が加えられる軸方向荷重を受けると、構造内で発生することがよくあります。 この実際の例は、橋のトラス部材に見られます。

ロッドに軸方向の荷重がかかると、内部力と対応する応力は断面の平面に対して垂直になるため、垂直応力と呼ばれます。 応力は特定の点ではなく、断面全体の平均応力値を表すことに注意することが重要です。 平均応力は、断面全体に分布する合力内部力の大きさを断面の面積で割ることによって計算されます。

<img alt="Equation1" src="/files/ftp_upload/15579/15579_Equation_1.svg" style="height: 42px;">

ただし、特定の点での応力はセクション全体で変化するため、平均応力とは異なる場合があります。 特にアキシアル荷重がかかる細いロッドでは、荷重の作用点付近で変動が大きくなることがあります。

平衡状態は、中心荷重を想定した場合、荷重適用点付近を除いて、軸方向に荷重がかかる部材の応力分布が均一であることを示しています。 ただし、偏心荷重は追加のモーメントにより不均一な応力を生成し、静的に不定な応力分布を示します。

軸方向の力を受けるロッドを考えてみましょう。その結果、断面積全体に抵抗力が発生し、これを応力と呼びます。SIは...

Education

JoVE Core

Mechanical Engineering

機械工学

Unit 1

ユニット1

Concept of Stress

ストレスの概念

KEY TERMS AND CONCEPTS

主要用語と概念

Normal Stress

normal stress in axial loading

Normal stress acts perpendicular to a material’s cross-sectional area. It appears when a force is applied along the axis of an object, which is called axial loading. Bridge truss members are a practical example of this kind of loading.

When a rod carries axial load, internal forces develop across the section. Because these forces act normal to the plane of the section, the stress is called normal stress. Stress here means the average stress over the whole cross-section, not the value at one exact point.

The average stress is found by dividing the resultant internal force by the cross-sectional area. The stress at a specific point can be different from that average, since it may vary across the section. In slender rods under axial load, that variation can be large near the points where the load is applied.

For a centric load, equilibrium suggests a uniform stress distribution in an axially loaded member, except near the load application points. Eccentric loading changes that pattern. It creates non-uniform stress because extra moments act on the member, so the stress distribution becomes statically indeterminate.

Normal Stress in Axial Loading

normal stress

Normal stress acts perpendicular to a material’s cross-sectional area. It appears when a force is applied along the axis of an object, which is called axial loading. Bridge truss members are a practical example of this kind of loading. When a rod carries axial load, internal forces develop across the section. Because these forces act normal to the plane of the section, the stress is called normal stress. Stress here means the average stress over the whole cross-section, not the value at one...

shearing stress

Shear Forces in Bolts and Rivets

Shearing stress is caused by transverse forces acting on an object. These forces create internal forces in the plane where the external forces are applied. The total internal force in that section is called the shear. Average shearing stress is found by dividing the shear by the cross-sectional area. This value is only an average, because shear stress is not spread evenly across the section. It can be zero at the surface and much higher than the average in other areas. Bolts, pins, and rivets...

bearing stress

Bolt-to-Plate Contact Pressure

Bearing stress is the contact pressure between two separate bodies. A common example is a bolt pushed through a plate. The bolt applies a force to the plate, and the plate pushes back with an equal and opposite force. That force is not a single point load. It is made up of many smaller forces spread across the contact surface between the bolt and the plate. Because these microforces are complex, engineers use an average value called bearing stress. Bearing stress is found by dividing the...

applications of stress

Boom and Rod Stress Analysis

Boom and rod stress analysis shows how a pinned support structure carries a load. The boom and the rod are connected by a pin and held in place by brackets and pins. The structure is then separated from its supports so the forces can be studied clearly. A free-body diagram is drawn to identify every force on the boom, the rod, and the load. The reaction forces on both members are found using equilibrium equations. At point P, the reaction causes compression in the boom. At point R, the...

stress on an oblique plane

Axial Load Stress on Inclined Sections

Axial loading creates stress in a material along its central axis. This kind of load can cause compression or elongation, and it produces normal stress. Normal stress acts perpendicular to the material area and can be either tensile or compressive. When the section is not perpendicular to the load, it becomes an oblique plane. On this inclined plane, the stress state includes both normal stress and shearing stress. Shearing stress acts parallel to the area and changes shape without changing...

stress: general loading conditions

Stress Components on a Loaded Body

Stress components on a loaded body can be found by cutting the body through a point with a plane parallel to the xy plane. That section carries the original loads, along with normal forces and shearing forces. The result is a simple way to describe how a structure responds under combined loading. The shearing force in the section can point in different directions within the plane. It is split into two parts that run parallel to the x and y axes. Each part is divided by the area, and as that...

components of stress

Stress Components on a Cube at a Point

Stress components on a small cube help describe how a body behaves under multiple loading. The cube is centered at point O and has stress acting on all six faces, whether the faces are visible or hidden. Normal stress components σx, σy, and σz act perpendicular to the x, y, and z axes. Shearing stress components also act on the cube faces. The visible faces carry shear stresses such as τxy and τxz. The hidden faces carry equal and opposite stresses. This balance keeps the cube in equilibrium.

design consideration

Safety Factors in Structural Design

Safety factors in structural design help engineers choose a material and loading limit that can be used safely. The process begins with a material’s ultimate strength. This value comes from tests that increase force until the material reaches its breaking point or limit. The ultimate load is then divided by the original cross-sectional area to find the ultimate normal stress, or strength. Ultimate shearing stress is another key value used in design. These limits show how much stress a material...

key terms and concepts

Learn how normal stress forms in axially loaded members, how to calculate average stress, and why stress can vary across a cross-section.

Normal Stress in Axial Loading | JoVE K12

JoVE Core 機械工学は、平衡、力、トラス解析、構造力学などの重要なトピックをカバーする簡潔でわかりやすいアニメーション ビデオを提供します。実際のアプリケーションを探索し、科学者主導の実験を通じてこれらのコンセプトが実際に動作しているのを目撃してください。

mechanical engineering

Normal Stress in Axial Loading

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