Is My Beam Hinge Pin Calculation Correct?

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Homework Help Overview

The discussion revolves around the calculation of a suitable size for a hinge pin in a beam system subjected to specific loading conditions. The problem involves determining reaction forces, maximum working shear stress, and the appropriate diameter for the pin, with a focus on shear strength and safety factors.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of reaction forces and maximum shear stress, with some questioning the methodology for determining the pin size based on shear stress. There is mention of the concept of double shear and its implications for allowable shear stress.

Discussion Status

Some participants express confidence in the calculations provided, while others seek clarification on the approach to calculating maximum shearing stress and determining pin size. There is an acknowledgment of the double shear condition affecting the allowable shear stress.

Contextual Notes

The discussion includes references to specific values such as shear strength and safety factors, as well as the need for accurate unit handling in calculations. The original poster's assumptions and provided data are under scrutiny, with participants exploring the implications of these factors on the calculations.

BIGEYE
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Appreciate if someone can check my answers to the following question:

A beam hinged at one end and simply supported at the other is subjected to the loading shown. A design calculation is required to determine the suitable size of hinge pin. If wrong, could you point me in the right direction.

Data Shear strength of pin material = 20 MN/m^2
Factor of safety = 5

Drawing of system can be found here:

http://img206.imageshack.us/img206/6549/oc2q3gc5.jpg a) Use these conditions to determine the reaction forces RP and R1b) State the maximum working shear stress in the pin.c) Calculate a suitable diameter for the pin to the nearest millimeter.a) My answers are RP = 1700 N, and R1 = 800 N.

b) My answer 4 MN/m^2

c) My answer = 16 mm
 
Last edited by a moderator:
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BIGEYE said:
Appreciate if someone can check my answers to the following question:

A beam hinged at one end and simply supported at the other is subjected to the loading shown. A design calculation is required to determine the suitable size of hinge pin. If wrong, could you point me in the right direction.

Data Shear strength of pin material = 20 MN/m^2
Factor of safety = 5

Drawing of system can be found here:

http://img206.imageshack.us/img206/6549/oc2q3gc5.jpg


a) Use these conditions to determine the reaction forces RP and R1


b) State the maximum working shear stress in the pin.


c) Calculate a suitable diameter for the pin to the nearest millimeter.


a) My answers are RP = 1700 N, and R1 = 800 N.

b) My answer 4 MN/m^2

c) My answer = 16 mm
Your answers look correct to me. The pin is in a classic case of double shear.
 
Last edited by a moderator:
Thanks for taking the time.
 
Determine Pin Size?

PhanthomJay said:
Your answers look correct to me. The pin is in a classic case of double shear.

hey guys .. I am just wondering how you went about calculating the maximum shearing stress in the pin, and from that determining pin size ...

your help would be of most value ..
Thanks in advance
 
komy said:
hey guys .. I am just wondering how you went about calculating the maximum shearing stress in the pin, and from that determining pin size ...

your help would be of most value ..
Thanks in advance
The allowable shear stress in the pin with a 5.0 safety factor is "given" as 20/5 = 4MN/m^2. However, the pin is in double shear, so effectively the allowable shear stress can be taken as twice that value (8MN/m^2). The 1700N pin force was calculated from statics. Pin shear stress is shear force divided by cross sectional area of pin (1700N/A = 8MN/m^2). Solve for A, then diameter; watch units and decimal point.

Please ask again if you don't understand the concept of double shear.
 
PhanthomJay said:
The allowable shear stress in the pin with a 5.0 safety factor is "given" as 20/5 = 4MN/m^2. However, the pin is in double shear, so effectively the allowable shear stress can be taken as twice that value (8MN/m^2). The 1700N pin force was calculated from statics. Pin shear stress is shear force divided by cross sectional area of pin (1700N/A = 8MN/m^2). Solve for A, then diameter; watch units and decimal point.

Please ask again if you don't understand the concept of double shear.


mate i totally understand it now ..
thanks for your help !
 

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