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

Consider a rod subjected to an axial force; as a result, a resistive force is developed across the cross-sectional area, which is termed as stress. The SI unit of stress is Newton per square meter.
Now, consider a bridge truss member subjected to an axial force. It develops internal forces and stress normal to the cross-sectional plane, called the normal stress.
The resultant normal stress represents an average stress over the cross-section, rather than at a specific point.
According to the conditions for equilibrium, the internal forces equals the applied force, implying that stress distribution is uniform, except near the point of application.
However, this uniform distribution is only possible if the line of action of the loads passes through the centroid of the section, termed centric loading.
When axial loading is applied eccentrically, the distribution of forces and stresses cannot be uniform or symmetric due to the additional moment created.
So, the actual stress distribution in an axially loaded member is statically indeterminate and depends on the specific mode of load application.

normale spanning

Normale spanning is een soort spanning die optreedt wanneer krachten loodrecht of normaal op de dwarsdoorsnede van een materiaal werken. Deze spanning ontstaat vaak in constructies, wanneer deze worden onderworpen aan axiale belasting, wat het uitoefenen van kracht langs de as van een object is. Een praktisch voorbeeld hiervan is te vinden in brugliggers.

Wanneer een staaf onder axiale belasting staat, zijn de interne krachten en de bijbehorende spanning loodrecht op het vlak van de sectie, dus dit wordt normale spanning genoemd. Het is belangrijk op te merken dat spanning, de gemiddelde spanningswaarde over de doorsnede vertegenwoordigt, en niet op een specifiek punt. De gemiddelde spanning wordt berekend door de grootte van de resulterende interne krachten, verdeeld over de doorsnede te delen door de oppervlakte van de doorsnede.

<img alt="Equation 1" src="/files/ftp_upload/15579/15579_Equation_1.svg" style="text-align: center; height: 42px;">
De spanning op een bepaald punt kan echter afwijken van de gemiddelde spanning, aangezien deze over de sectie varieert. Vooral bij slanke staven onder axiale belastingen kan de variatie aanzienlijk zijn nabij de belastingspunten.

Evenwichtsomstandigheden suggereren een uniforme spanningsverdeling in axiaal belaste elementen, behalve in de buurt van belastingspunten, uitgaande van centrische belasting. Excentrische belasting veroorzaakt echter niet-uniforme spanning, als gevolg van extra momenten, wat wijst op een statisch onbepaalde spanningsverdeling.

Normale spanning

Consider a rod subjected to an axial force; as a result, a resistive force is developed across the cross-sectional area, which is termed as stress. The SI ...

Education

JoVE Core

Mechanical Engineering

Werktuigbouwkunde

Unit 1

Concept of Stress

Het concept van stress

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

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 Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

Normal Stress in Axial Loading

Description

Transcript

Tags