Name: 3d support types for stability and motion
Uploaded: 2023-09-22T11:49:23.000Z
Duration: 1 min 27 s
Channel: JoVE

A variety of supports are employed in mechanical engineering based on their application.&#160; These support reactions in a three-dimensional force system prevent the system from translating and rotating.
Consider a robotic arm lifting a weight. Here, joint A is a ball and socket joint. The arm is free to rotate about any axis as there is no moment to restrict the rotation in the ball and socket joint. However, it restricts translational motion because of the three reaction forces along the three dimensions.
Alternately joint B on the arm is a single smooth pin support. This support creates three reaction forces and two couple moments and allows the rotational motion along the axis of the pin.
The base of the robotic arm is fixed support, having reaction forces and moments along all three directions.
Another type of support is hinge support, used commonly in a door. Three reaction forces at the support restrict the translational motion of the door, while two moments restrict the rotation of the door.

support reactions in three dimensions

Support Reactions in Three Dimensions

Support reactions in three dimensions help maintain the stability and equilibrium of various structures and systems. These reactions prevent the system from translating and rotating, ensuring the design can withstand external forces and perform its intended function efficiently and safely. Some of the supports providing support reactions in three dimensions are discussed below:
Ball and Socket Joint is one of the supports allowing free rotation about any axis. This freedom of rotation is possible because there is no moment restricting the rotation in the ball and socket joint. However, the joint restricts translational motion due to three reaction forces along the three dimensions.
Another type of support is the single smooth pin support. This support creates three reaction forces and two couple moments, allowing rotational motion along the axis of the pin while restricting movement in other directions.
Fixed supports provide reaction forces and moments along all three directions. This type of support ensures that the entire system remains stable and secure under various loads and conditions, preventing unwanted movement or deformation that could compromise the system&#39;s functionality.
Hinge support is another common type of support employed in mechanical engineering, often used in doors and other similar applications. With hinge support, three reaction forces at the support restrict the translational motion of the door, while two moments restrict the rotation of the door. This arrangement allows the door to rotate about a single axis while maintaining stability and control.

Support reactions in three dimensions help maintain the stability and equilibrium of various structures and systems. These reactions prevent the system ...

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Equilibrium of a Rigid Body

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3d support types for stability and motion

Support reactions in three dimensions keep structures stable and in equilibrium. They stop unwanted translation and rotation, so a design can handle external forces safely and work as intended. These reactions are important in many structures and systems.

A ball and socket joint is one support that allows free rotation about any axis. It does not provide a moment that resists turning. At the same time, it restricts motion in space with three reaction forces along the three dimensions.

A single smooth pin support works differently. It creates three reaction forces and two couple moments. This setup allows rotation along the axis of the pin while restricting movement in the other directions.

Fixed supports provide reaction forces and moments in all three directions. They help keep the system stable and secure under different loads and conditions. This also helps prevent unwanted movement or deformation that could affect function.

Hinge support is another common support used in mechanical engineering, especially in doors and similar applications. It produces three reaction forces that block translational motion of the door. Two moments restrict the door’s rotation, but it can still turn about one axis.

3D Support Types for Stability and Motion

3d-support-types-for-stability-and-motion

conditions of equilibrium

Rigid Body Force Balance in Equilibrium

Rigid body equilibrium depends on a balance of external forces and moments. A rigid body is in equilibrium when it has no translational motion and no rotational motion. This happens when the net force and the net couple acting on the body are both zero. Internal forces are not used when checking equilibrium. These forces act in equal and opposite pairs inside the body, so they cancel each other. Because of that, they do not affect the overall motion or change in motion of the rigid body. The...

support reactions

Types of Structural Supports

Types of structural supports control how a coplanar force system moves and reacts under load. A coplanar force system is a set of forces that all lie in the same plane. The supports create reactions at the point of contact. These reactions help keep a structure stable under external forces. Supports work by stopping translation with an equal and opposite force. They can also stop rotation by applying a couple moment in the opposite direction. In structural design, these reactions are important...

internal forces and center of gravity

Forces Inside a Body and Balance

Internal forces and the center of gravity help explain how objects stay in balance. These mechanics ideas matter for structures, machines, and vehicles that must remain stable under different loads and conditions. Internal forces are created inside a body when its particles interact. They can appear as tension, compression, or shear forces. These forces act in collinear pairs with equal magnitude and opposite direction. Between connected parts, they cancel each other and help keep the body in...

alternative sets of equilibrium equations

alternative-sets-of-equilibrium-equations

Equilibrium Conditions for a Supported Plate

Equilibrium conditions for a supported plate are used to describe when forces and moments balance. In this state, the plate has no net movement and no rotation. Engineers use these equations to study how structures behave under external loads. In many cases, the standard equilibrium equations are enough. But some systems need an alternative set of equations to match the geometry of the support points. A rectangular plate supported at points A, B, and C is one example. For this plate, the...

two force member

Two-Force Body Equilibrium

A two-force body is a rigid body acted on by only two external forces. In equilibrium, those two forces must have the same magnitude, the same line of action, and opposite directions. This balance is what keeps the body at rest. For a plate with forces F1 and F2 applied at points A and B, equilibrium means the sum of moments about any axis is zero. If moments are summed about point A, the moment from F2 must be zero. That means the line of action of F2 must pass through point A. The same idea...

three force member

Solving a Three-Force Member Example

A three-force member is a rigid body acted on by three forces at three points. The forces must have concurrent lines of action. If the forces are parallel, their lines of action stay parallel instead. A dumpster provides the example used here. It is connected to a pin support at point A and to a pin on a hydraulic cylinder at point B. The hydraulic cylinder acts as a two-force member in equilibrium. The dumpster weight acts through the center of gravity, and the support reaction acts at point...

equations of equilibrium in three dimensions

equations-of-equilibrium-in-three-dimensions

Checking Force Balance in 3D Structures

Checking force balance in 3D structures is a key step when a system is at rest. The vector and scalar equations of equilibrium are used to test whether a body is stable and will not collapse or fall apart. These equations give a clear way to study the forces acting on a body. The vector equations of equilibrium require the vector sum of all external forces on a body to equal zero. They also require the vector sum of the couple moments and the moments of all forces about a point to equal zero.

Support reactions in three dimensions keep structures stable and in equilibrium. They stop unwanted translation and rotation, so a design can handle external forces safely and work as intended. These reactions are important in many structures and systems. A ball and socket joint is one support that allows free rotation about any axis. It does not provide a moment that resists turning. At the same time, it restricts motion in space with three reaction forces along the three dimensions. A...

constraints and statical determinacy

Constraints in Structural Equilibrium

Constraints in structural engineering control how a body can move and help keep it in mechanical equilibrium. A constraint is a restriction on motion. When the right number of constraints is used, the system can stay balanced with the fewest supports needed. A system with the proper number of supports is called statically determinate. In that case, the unknown reaction forces can be found from equations of equilibrium. These systems are the easiest to analyze and design because the forces can...

key terms and concepts

Learn how ball and socket joints, smooth pin supports, fixed supports, and hinge supports control movement and keep 3D structures stable under load.

3D Support Types for Stability and Motion | JoVE K12

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3D Support Types for Stability and Motion

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