Mechanical Engineering Design Question and answers

VAAL UNIVERSITY OF
TECHNOLOGY

Cover sheet for RETEST3

Faculty: Engineering
Department: Mechanical
Diploma: National Diploma: Engineering: Mechanical
Subject: Mechanical Engineering Design II
Date: 30 JULY 2021`
Internal code: EMMED2A
Examiner: MD Mafoko
Moderator: AO Aniki
Hours: 90 min

Total Marks: 60 Full marks: 60

* Requirements: OPEN BOOK ASSESSMENT

* Instructions: Answer all the questions. Show all your work.


Signature of Examiner:…MD Mafoko……… Date: 27 JULY 2021

Signature of Moderator:…Abimbola Aniki….. Date:………………

, Q1. A knuckle joint is loaded with a 90 kN tensile force. The joint is made from material

with allowable shear stress of 20 MPa. If this load causes shearing of the single eye whose

thickness is 1,5 times the solid rod diameter, determine the diameter of the pin using

standard sizes.

Given F= 90 K

Allowable shear stress τ = 20 MPa

Thickness of eye teye= 1,5 x diameter of pin

According to standard sizes

Fs=2 x dpin x teye x τ

Standard sizes diameter of pin = diameter of solid rod

dpin = ds

90 kN= dpin x ds x τ

90 kN = dpin x 1,5dpin x τ

90 kN =2 x 1,5d2pin x 20 MPa OR
90 𝑘𝑁
= 3d2pin OR
20 𝑀𝑃𝑎

90 𝑘𝑁
= d2pin OR
3 𝑥 20 𝑀𝑃𝑎

d2pin = 1,5 x 10 -3 m2

dpin = 0,03873 m

dpin = 38,73 mm

Standard size is 39 mm

5 marks.