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MACHINE DESIGN  An
3131
PROBLEM 313
Statement:
Determine the impact force and dynamic deflection that will result when a 100kg person
jumps up 25 cm and lands back on the board.
Assume the board weighs 19 kg and deflects 8.5 cm statically
when the person stands on it.
Find the reaction forces and construct the shear and moment diagrams for this
dynamic loading.
Determine the maximum shear force, maximum moment, and their locations along the
length of the board.
Units:
kN
10
3
newton
.
N
newton
2000
1300
= L
R
1
700
M
1
F
i
Given:
Total board length
b
2000
mm
.
Supported length
a
700
mm
.
Mass of board
m
board
19
kg
.
Static board deflection
δ
stat
85
mm
.
Mass of person
m
person
100
kg
.
Height of jump
h
250
mm
.
Assumptions:
1. The board can be modelled as a cantilever
beam with maximum shear and moment at
the edge of the support.
FIGURE 313A
Free Body Diagram for Problem 313
Solution:
See Figure 313 and Mathcad file P0313.
1.
The person impacts the board upon landing.
Thus, the board is the struck object and the person is the striking
object.
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This note was uploaded on 04/26/2010 for the course MAE 3242 taught by Professor N/a during the Spring '10 term at University of TexasTyler.
 Spring '10
 N/A
 Machine Design

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