• H20Kid
In summary, a member is trying to get a rough estimate of a safe load capacity for a "lifting bar" . The material is 1" diameter x 36" long, 1045 steel bar with a lifting D- Ring centered on it. Every equation that the member has looked into shows deflection of beams supported at two ends with the load in the center... what is the appropriate way to determine how much load can safely be hoisted? The member wants this to be as safe as possible, but is worried about the safety of the activity and the safety of the material being lifted.
H20Kid
Hey everyone,

I am not a structural engineer; so I thought maybe I could get some help understanding the concepts of a project I am trying to complete. I am trying to get a rough estimate of a safe load capacity for a "lifting bar" .

The material itself is 1" diameter x 36" long 1045 steel bar. A lifting D- Ring will be centered on this bar as a lifting point.

Every equation that I have looked into shows deflection of beams supported at two ends with the load in the center... What is the appropriate way to determine how much load can safely be hoisted...Loads on the ends of the beam with a suspended center point V----------^----------V ??

Any help would be appreciated...want this to be as safe as possible

Turn your reference up side down. With that,the upward force is in the center, and the downward forces are at the ends.

Thank you.. I pondered over that... but is it in fact the same? Because the center lift point theoretically isn't applying an upward force..the two sides are just applying downward force on a center supported object? Or is it and I am over thinking it?

H20Kid said:
Hey everyone,

I am not a structural engineer; so I thought maybe I could get some help understanding the concepts of a project I am trying to complete. I am trying to get a rough estimate of a safe load capacity for a "lifting bar" .

The material itself is 1" diameter x 36" long 1045 steel bar. A lifting D- Ring will be centered on this bar as a lifting point.

Every equation that I have looked into shows deflection of beams supported at two ends with the load in the center... What is the appropriate way to determine how much load can safely be hoisted...Loads on the ends of the beam with a suspended center point V----------^----------V ??

Any help would be appreciated...want this to be as safe as possible

H20Kid said:
Thank you.. I pondered over that... but is it in fact the same? Because the center lift point theoretically isn't applying an upward force..the two sides are just applying downward force on a center supported object? Or is it and I am over thinking it?

Welcome to the PF.

Can you say more about your project? What will you be lifting? Is this project for schoolwork, or a personal project? If it is for schoolwork, do you have an adviser that you can talk this through with?

Hey Berkeman; this is a personal project...unfortunately I have no adviser at my side :) ... This is going to be used for lifting granite...I will have a steel shaft suspended from a center lifting point...on this shaft will be rollers. They make these to buy...but I wanted to make my own; but I do need it to be safe...for my personal safety and for the liability of the merchandise in the air. I am using the same material that is used in the production models you can buy with slight differences... I just want to learn how to do the math for my own benefit.

H20Kid said:
Hey Berkeman; this is a personal project...unfortunately I have no adviser at my side :) ... This is going to be used for lifting granite...I will have a steel shaft suspended from a center lifting point...on this shaft will be rollers. They make these to buy...but I wanted to make my own; but I do need it to be safe...for my personal safety and for the liability of the merchandise in the air. I am using the same material that is used in the production models you can buy with slight differences... I just want to learn how to do the math for my own benefit.

That's the issue that I have with this thread. We don't allow discussion of dangerous activities here, and helping you analyze the safety of a mechanical lifting device (when you have no experience or training in that analysis and math) could be a bad idea. I've asked for the opinions of the other Mentors. I'll temporarily close this thread until we can decide how to handle it.

After a Mentor discussion, this thread will remain closed. Please consider investing in the off-the-shelf solution.

What is deflection and safe load?

Deflection is the bending or deformation of a material when a force is applied. Safe load is the maximum amount of force that can be applied to a material without causing it to fail or break.

Why is it important to know the deflection and safe load of a material?

Knowing the deflection and safe load of a material is important for engineering and construction purposes. It ensures that the material is able to withstand the expected forces and loads without failure, which can lead to structural damage or injury.

How is the deflection and safe load of a material determined?

The deflection and safe load of a material are determined through testing and calculations. The material's properties such as strength, stiffness, and elasticity are taken into account to determine its behavior when subjected to different forces.

What factors can affect the deflection and safe load of a material?

The deflection and safe load of a material can be affected by various factors such as its composition, shape, size, and environmental conditions. Other factors like the type and direction of the force applied can also impact the material's behavior.

How can deflection and safe load be improved?

Deflection and safe load can be improved by using materials with higher strength and stiffness, increasing the size or thickness of the material, and using reinforcement techniques such as adding support structures. It is also important to properly design and engineer the structure to distribute the load evenly and minimize stress on the material.

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