Name: checking force balance in 3d structures
Uploaded: 2023-09-22T11:49:23.000Z
Duration: 1 min 30 s
Channel: JoVE

Considere um tripé colocado no chão; sua perna é conectada usando uma junta esférica em A e a outra extremidade B está no chão.
Quando a força resultante e o momento do par resultante atuando na perna são zero, diz-se que a perna está em equilíbrio e pode ser expressa com a ajuda de equações de equilíbrio.
Como a perna está em equilíbrio, ela satisfaz as equações vetoriais e escalares de equilíbrio.
De acordo com as equações vetoriais de equilíbrio, todas as forças externas que atuam na perna devem ter uma soma vetorial de zero. A soma vetorial de todos os momentos de casal e os momentos de todas as forças em torno de um ponto também devem ser iguais a zero.
De acordo com as equações escalares de equilíbrio, se as forças externas são expressas na forma cartesiana, então a soma do componente das forças ao longo das respectivas direções deve ser zero.
Da mesma forma, a soma escalar dos componentes de um momento nos eixos x, y e z também deve ser zero.

<ol>
	<li>Hibbeler, R.C. (2016). Engenharia Mecânica \u2012 Estática e Dinâmica. Hoboken, Nova Jersey: Pearson Prentice Hall. pág. 250</li>
</ol>

equações de equilíbrio em três dimensões

Equations of Equilibrium in Three Dimensions

Ao analisar estruturas ou sistemas em repouso, é necessário garantir que eles estejam em equilíbrio. É aí que entram em jogo as equações vetoriais e escalares de equilíbrio. Essas equações são cruciais para garantir que uma estrutura seja estável e não irá colapsar ou se desfazer. As equações vetoriais e escalares de equilíbrio fornecem um quadro para analisar as forças atuando em um corpo.

De acordo com as equações vetoriais de equilíbrio, a soma vetorial de todas as forças externas atuando em um corpo deve ser igual a zero. Além disso, a soma vetorial de momentos de um casal e os momentos de todas as forças em relação a um ponto também devem ser iguais a zero.

<img alt="Equation 1" src="/files/ftp_upload/14275/14275_Equation_1v2.svg" style="text-align: center; height: 33px;" />

As equações escalares de equilíbrio afirmam que, se as forças externas forem expressas na forma cartesiana, então a soma das componentes das forças ao longo das direções respectivas deve ser zero.

<img alt="Equation 2" src="/files/ftp_upload/14275/14275_Equation_2v2.svg" style="text-align: center; height: 55px;" />

De forma similar, a soma escalar das componentes de um momento nos eixos x, y e z também deve ser zero.

<img alt="Equation 3" src="/files/ftp_upload/14275/14275_Equation_3v2.svg" style="text-align: center; height: 55px;" />

Essas equações são fundamentais na engenharia mecânica, garantindo que as estruturas sejam seguras e estáveis.

Equações de Equilíbrio em Três Dimensões

Ao analisar estruturas ou sistemas em repouso, é necessário garantir que estejam em equilíbrio. É aqui que as equações vetoriais e escalares de ...

equations-of-equilibrium-in-three-dimensions

Education

JoVE Core

Mechanical Engineering

Engenharia Mecânica

Unit 1

Unidade 1

Equilibrium of a Rigid Body

Equilíbrio de um Corpo Rígido

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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. A couple moment is a turning effect produced by a pair of forces.

The scalar equations of equilibrium use Cartesian form, which means the forces are written in x, y, and z components. In that form, the sum of the force components along each direction must be zero. The scalar sum of the moment components about the x, y, and z axes must also be zero. These conditions are fundamental in mechanical engineering because they help show that structures are safe and stable.

Checking Force Balance in 3D Structures

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

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

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...

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 vector and scalar equilibrium equations keep 3D structures stable by balancing forces and moments in x, y, and z directions.

Checking Force Balance in 3D Structures | JoVE K12

O JoVE Core Mechanical Engineering oferece vídeos animados concisos e de fácil compreensão que abrangem tópicos-chave como equilíbrio, forças, análise de treliças e mecânica estrutural. Explore suas aplicações no mundo real e observe esses conceitos em ação por meio de experimentos conduzidos por cientistas.

mechanical engineering

Checking Force Balance in 3D Structures

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