MECH324 - Homework Hints and Answers

MECH324 - Homework Hints, Answers, and Extra Requirements

Homework 10 (Chapters 12 and 15)

TO ENHANCE YOUR LEARNING, PLEASE TRY TO WORK THE PROBLEMS FIRST WITHOUT LOOKING AT THE HINTS AND ANSWERS BELOW.

MAKE SURE YOU SATISFY ALL REQUIREMENTS LISTED BELOW AND IN THE ORIGINAL PROBLEM STATEMENTS (UNLESS INDICATED OTHERWISE BELOW).

NOTE - BECAUSE MOST ANSWERS ARE PROVIDED, IT IS VERY IMPORTANT THAT YOU SHOW ALL STEPS IN YOUR WORK. THE GRADING WILL BE BASED ON THE COMPLETENESS, CLARITY, AND CORRECTNESS OF YOUR WORK, NOT JUST THE ANSWERS YOU PROVIDE.

12-1a
[20 pts]

For units, assume "kg" for mass and "m" for radius.
F_s = 93 N
mR_b = 0.934 kg m
θ_b = -75.5°

12-5a
[30 pts]

For units, assume "kg" for mass and "m" for radius and length.
F_s = 680 N
M_Os = 12100 N m
m_BR_B = 5.50 kg m
θ_B = 152°
m_AR_A = 0.814 kg m
θ_A = -175°

15-18
[50 pts]

You are not allowed to use program DYNACAM for this problem. You must do the analysis yourself and show all work.
Use a 3-4-5 polynomial for both the rise and the fall segments to limit the peak acceleration.
Assume the rise and fall each last 40°. This leaves 80° for the high dwell.
Assume a spring preload of 1200 N.
Plot the cam force over the rise-fall period to show there is no valve float (jump). Explain your results.
FYI, you do not need the roller follower size to determine the cam force.

12-1a [20 pts]	For units, assume "kg" for mass and "m" for radius. F_s = 93 N mR_b = 0.934 kg m θ_b = -75.5°
12-5a [30 pts]	For units, assume "kg" for mass and "m" for radius and length. F_s = 680 N M_Os = 12100 N m m_BR_B = 5.50 kg m θ_B = 152° m_AR_A = 0.814 kg m θ_A = -175°
15-18 [50 pts]	You are not allowed to use program DYNACAM for this problem. You must do the analysis yourself and show all work. Use a 3-4-5 polynomial for both the rise and the fall segments to limit the peak acceleration. Assume the rise and fall each last 40°. This leaves 80° for the high dwell. Assume a spring preload of 1200 N. Plot the cam force over the rise-fall period to show there is no valve float (jump). Explain your results. FYI, you do not need the roller follower size to determine the cam force.