Question

Astock helical-coll compression spring has a total of 14 colls, both ends squared and ground, a free length of 1.25 in, and an outside coll diameter of 7/16(0438) in giving the number of active colls, N, 12. The material is hard-drawn wire 0.042-inch in diameter and S,259.000 psl. The operating forces are Fin" 1.5 lb and Fax 3.5lb. VODOM 0.438 in N 14 coils 0012 in die 125 intro length Note, choose one or more than one of the following MC answers and then type the letter(s) corresponding to the question number in the essay section of this problem with supporting calculations contained on the scratch sheet. If the answer requires the correct answer is "type that in the essay section as well. 1a) Force-deflection plot is shown on scratch sheet Develop the force deflection curve for the working load to show that the range of operating deflections that are possible and determine the spring constant. 16) For the spring design a) Spring Index, C 943 b) Spring Index, C4.93 Shear correction factor KIS 105 d) Maximum stress in this spring is a normal stress e) All of the above None of the above, the correct answers 1c) FS against failure if compressed to solidength: al 5.3 at sold length 0,59 in b) FS23 st sold onth of 0.59 c) Solid length is 0.662 in at FS416 d) 51 sollength e) A n None of the above the crawwers above

Answer 1

Given

No of coils	14		14
Free length	1.25	in	31.75	mm
OD	0.438	in	11.1252	mm
n	12		12
n'	14		14
d	0.042	in	1.0668	mm
G			80000	N/m^2
F min	1.2	lb	5.339685	N
F max	3.5	lb	15.57408	N

the stiffness of the spring or spring rate, W 8 8 Din G.d4

Spring rate W/δ	4.477	lb/in	0.784	N/mm
Spring Index C = D/d			10.42857
Deflection F max, δmax	0.782	in	19.87	mm
Deflection F min	0.268	in	6.81	mm
Shear factor Ks = 1+ (1/2C)	1.05

Load deflection chart is given below

Deflection 4.000 3.500 3.000 22.500 Load in lb 2.000 1.500 -Deflection 1.000 0.500 0.000 0.000 0.500 1.000 1.500 Deflection in inches

Spring Index

Spring Index D/d

10.42857

Shear factor Ks = 1+ (1/2C)

1.04794521

Rounding off

Shear factor Ks = 1+ (1/2C)

1.05

Shear correction factor is 1.05 and is true

  

1d) Spring performance is: 1. a) The spring constant is k=6 lb/in 2.b) Deflection at 3 lb is 0.58 in 3.) Spring constant is 4 lb/in 4. d) Shear stress is of concern in axially-loaded helical springs 5. e) All of the above 6. f) None of the above, the correct answer is:

Load	3	lb	13.34921	N
Deflection at 3 lb	0.670	in	17.03054	mm

Spring rate is 4 rounding off

4 is actually true, for axially loaded spring.

the stiffness of the spring or spring rate, W 8 8 Din G.d4

Deflection 4.000 3.500 3.000 22.500 Load in lb 2.000 1.500 -Deflection 1.000 0.500 0.000 0.000 0.500 1.000 1.500 Deflection in inches

1d) Spring performance is: 1. a) The spring constant is k=6 lb/in 2.b) Deflection at 3 lb is 0.58 in 3.) Spring constant is 4 lb/in 4. d) Shear stress is of concern in axially-loaded helical springs 5. e) All of the above 6. f) None of the above, the correct answer is: