Name: lifting tong force analysis
Uploaded: 2023-09-22T11:49:25.000Z
Duration: 1 min 30 s
Channel: JoVE

100kgの荷物を運ぶリフティングトングを考えてみましょう。これは、メンバーABとリンクされた可動セクションDAFおよびCBGで構成されています。
構造が点Eに対して対称であると仮定すると、メンバーABにはどのような力が作用しているのでしょうか?
点Eに作用する力を示す自由体図が描画されます。
ケーブルの張力は、負荷の重量を釣り合い、垂直に上向きに作用します。
EDとECは2つの力のメンバーです。したがって、力FEDとFECは、それぞれジョイントDとCに向けられます。
これらの力は水平成分と垂直成分に分解され、構造物の形状が適用されて、部材EDと水平力成分との間の角度が決定されます。
水平方向に沿って力の平衡条件を適用すると、FEDがFECと等しくなります。
同様に、垂直方向の力平衡条件では、部材EDに沿った力が得られます。
次に、セクション DAF のフリーボディ ダイアグラムについて考えてみます。モーメント平衡条件は、ジョイントFに適用できます。 
すべての既知の値を方程式に代入すると、メンバーABに沿った力が得られます。

<ol>
	<li>ヒベラー、RC(2016)。エンジニアリングメカニクス \u2012 静力学と力学。ニュージャージー州ホーボーケン:ピアソンプレンティスホールPppp 305。</li>
	<li>ビール、FP;ジョンストン、ER;マズレック、D.F;クロムウェル、PJおよびセルフ、BP(2019)。エンジニアのためのベクトル力学 \u2012 静力学と動力学。ニューヨーク:マグロウヒル。348ページ</li>
	<li>メリアム、JL、クレイジ、LG、およびボルトン、JN(2020)。エンジニアリングメカニクス \u2012 静力学。ニュージャージー州ホーボーケン:ジョン・ワイリー。200ページ</li>
</ol>

利益相反は宣言されていません。

機械：問題解決 ii

機械は動かせるピン接続の多力部材からなる複雑な構造であり、力を伝達するために協力して働きます。100 kgの荷物を運ぶための持ち上げトングを考えてみましょう。それは動かせるセクションDAFとCBGからなり、部材ABで結合されています。

構造が点Eで対象的であると仮定すると、部材ABにかかる力を計算することができます。

まず、点Eで作用する力を示す自由体図を考えます。重力による加速度の質量倍数と等しい荷物の重さは981 Nとして計算されます。ケーブルのテンション力は荷物の重さと釣り合い、垂直方向に向かって働きます。EDとECは2力部材です。その結果、力FEDとFECはそれぞれ接合点DとCに向かっています。

次に、力FEDとFECを水平方向と垂直方向の成分に分解します。構造の幾何学的な特性から、部材EDと水平方向の力成分の間の角度は30.96度と計算されます。

力の平衡条件は接合点Eに適用することができます。

水平方向の力の平衡条件を適用すると、FED はFECに等しいことが保証されます。同様に、垂直方向の力の平衡条件により、部材EDに沿った力は953.46 Nとなります。

次に、セクションDAFに対する自由体図を考えます。モーメントの平衡条件を接合点Fに適用することができます。

結果として、部材ABに沿った力は2423.76 Nとなります。

この持ち上げトングシステムの各部材に作用する力を理解することは、安全な操作と効率的な持ち上げ機構の設計に不可欠です。力を分析し平衡条件を適用することにより、エンジニアは構造を最適化し、さまざまな条件下で安全に荷物を運ぶことができるようにします。

機械：問題解決 II

機械は、ピンで接続された可動式のマルチフォース部材で構成され、それらが連携して力を伝達する複雑な構造です。リフティングトングを考えてみましょう...

Education

JoVE Core

Mechanical Engineering

機械工学

Unit 1

ユニット1

Structural Analysis

構造解析

KEY TERMS AND CONCEPTS

主要用語と概念

Machines: Problem Solving II

lifting tong force analysis

Lifting tong force analysis shows how forces move through a pin-connected machine. The structure uses movable sections DAF and CBG with member AB linking them together. Because these parts work as connected members, the load can be studied with equilibrium methods.

The example starts with a 100 kg load at point E. The load weight is found by multiplying mass by gravity, which gives 981 N. The cable tension acts upward and balances that weight. Since the structure is symmetrical at E, the forces on the two sides can be compared.

Members ED and EC are two-force members, so their forces act along the members toward joints D and C. Their forces are then split into horizontal and vertical parts. Using the geometry of the tong, the angle between member ED and the horizontal is 30.96 degrees. Force equilibrium at joint E shows that F ED equals F EC, and the vertical balance gives the force in member ED as 953.46 N.

After that, a free-body diagram for section DAF is used. The moment equilibrium condition is applied at joint F. This step gives the force in member AB as 2423.76 N. This kind of analysis helps engineers check the forces in each member so lifting systems can work safely and efficiently under load.

Lifting Tong Force Analysis

introduction to structures

Structure Types and Force Paths

Structures are systems of interconnected members that support or transfer forces and handle the loads placed on them. Engineers can find the internal forces in a structure by breaking it apart and drawing free-body diagrams for individual members or groups of members. This helps show how structural elements behave and how the whole system stays stable under load. There are three main categories of structures: trusses, frames, and machines. Trusses are stationary structures that stay rigid when...

simple trusses

Simple Trusses and Triangular Frames

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The method of joints is used to find the forces in structural trusses. It relies on equilibrium, which means the forces at a joint must balance. In this model, the truss members are connected by frictionless pins. For a plane truss, the members lie in the same plane. That means each joint has a coplanar and concurrent force system. The analysis begins by identifying and labeling all the joints in the truss. Next, each joint is isolated and shown in a free-body diagram. This diagram includes...

method of joints: problem solving i

Truss Joint Force Analysis by Equilibrium

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method of joints: problem solving ii

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zero-force member

Finding Zero-Force Members in Trusses

Trusses are frameworks made of slender members that connect at their ends by joints. Engineers and architects use them to stabilize and strengthen structures such as bridges, roofs, and towers. Truss members carry loads through tension and compression so the structure can handle external forces. A key part of truss analysis is spotting zero-force members. A zero-force member is a truss member that carries no stress under loading conditions. During analysis, some members may show zero force,...

method of sections

Truss Member Force Analysis by Sections

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method of sections: problem solving i

Truss Member Force Calculation by Sections

Truss member forces can be found with the method of sections in a symmetrical roof truss. The structure here includes vertical, diagonal, and horizontal members. Each horizontal member is 4 m long. The vertical members FB and HD are 4 m long, and member GC is 6 m long. The roof truss carries loads at several joints. Joints F, G, and H each have a 2 kN load. Joints A and E each have a 1 kN load. To start the analysis, moment equilibrium is used at point A. The force and distance values are...

method of sections: problem solving ii

Truss member force analysis by sections finds the forces in selected members of a wall-mounted truss. The structure here includes diagonal, vertical, and horizontal members. The known loads and member lengths are used to solve for the forces in CB, GB, and GH. A cut is made through members CB, GB, and GH. The right side of the truss is then isolated as a free-body diagram. Next, the moment equilibrium equation is taken about point G. This step gives the force in member CB as 4 kN, and the...

space trusses

Space Truss Forces and Stability

A space truss is a three-dimensional truss made from members joined at their ends. It is the 3D version of a planar truss. These frameworks often use ball-and-socket joints, which help the structure stay stable and flexible under load. Space trusses are used in many construction projects because they can adapt to complex forces. Their basic building block is the tetrahedron. A tetrahedron has six members and four triangular faces. Engineers can build larger space trusses by adding one joint...

space trusses: problem solving

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frames

Frame Analysis in Structural Systems

Frames are important parts of many mechanical and structural systems used every day. They are valued for stability and for their ability to bear heavy loads. A frame is built from two-force members and multi-force members, and the parts are connected with pin joints. Trusses are different because they are made entirely of two-force members. Frames appear in many practical settings. They can support beams and columns in buildings. They are also used in automobile chassis construction. In the...

frames: problem solving i

Jib Crane Reaction Forces in Frames

Jib crane reaction forces in frames are found by analyzing the pin joints, the cable tension, and the load carried by the pulley. The structure in this problem has an external load suspended from the pulley, and the member sizes are shown in the figure. Because the pulleys are frictionless, the force balance can be worked out step by step. The frame has two main parts. Member BD is a two-force member, which means it is a straight part loaded only at its two ends, D and B. Those end forces are...

frames: problem solving ii

Hydraulic Hoist Force Analysis

Hydraulic hoist force analysis shows how to find the forces in key members of a simple frame. The load is 1 kN, and the structure is represented with known member dimensions. In this setup, BF and BD act as two-force members. EFG and EDC are multi-force members, so each one is analyzed with a free-body diagram. The first step is to study member EFG. The inclined force in BF is split into vertical and horizontal parts. Then the moment equilibrium condition is applied at joint E. Using this...

machines

Cutting Pliers as a Force-Multiplying Machine

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machines: problem solving i

Toggle Clamp Force Analysis

A toggle clamp can be analyzed to find its clamping force from a known handle force. In this example, a 200 N force is applied at the handle. The clamp is used in holding and clamping tasks in woodworking, metalworking, and assembly operations. The toggle clamp is a machine structure made of movable, pin-connected multi-force members. These members form a stabilized system that transmits force. Member CD is a two-force member, which means the forces at its ends are equal in magnitude and...

machines: problem solving ii

Lifting tong force analysis shows how forces move through a pin-connected machine. The structure uses movable sections DAF and CBG with member AB linking them together. Because these parts work as connected members, the load can be studied with equilibrium methods. The example starts with a 100 kg load at point E. The load weight is found by multiplying mass by gravity, which gives 981 N. The cable tension acts upward and balances that weight. Since the structure is symmetrical at E, the...

key terms and concepts

Analyze a lifting tong with pin-connected members, symmetry, and equilibrium. See how force, tension, and moments determine the load on member AB.

Lifting Tong Force Analysis | JoVE K12

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mechanical engineering

Lifting Tong Force Analysis

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