DOI : 10.17577/IJERTV2IS80240
- Open Access
- Total Downloads : 1730
- Authors : K. S. Bodadkar, Prof. S. D. Khamankar
- Paper ID : IJERTV2IS80240
- Volume & Issue : Volume 02, Issue 08 (August 2013)
- Published (First Online): 13-08-2013
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
Stress Analysis Of Riveted Butt Joint
K. S. Bodadkar *1
*Pg. student of Department of Mechanical Engineering
R.C.E.R.T. Chandrapur, India
Prof. S. D. Khamankar **2
**Associate Professor Department of Mechanical Engineering
R.C.E.R.T. Chandrapur, India
Abstract
Riveted joints are used in many structural works like ship buildings, in bridge structure and in manufacturing of boiler shells etc. The failures of riveted joint takes place by tearing of the plate, shearing of rivet and crushing of rivet and plate under the action of overloading. Hence the stress pattern in riveted butt joint by varying parameters like thickness of plate, linear pitch, transverse pitch and method of riveting is studied. In this research, analytical, numerical and experimental stress analyses are carried out. For analysis purpose virtual model of riveted butt joint is prepared in Pro-E. And this CAD model is imported in ANSYS software where stress analysis is done by FEM. This analysis shows that, to have safe joint it is better to increase the thickness of main plate and linear pitch instead of increase in transverse pitch. Also the analysis shows that von-mises stresses obtained in chain riveting are lesser as compared to diamond and zig-zag riveting. From this, it can be concluded that chain riveting is the most safe method of riveting. From the analysis, it is revealed that the analytical results obtained are in good agreement to F.E.A results.
Keywords: FEM, Riveted Joints, Shearing stress, Tearing stresses
-
Introduction
For nearly a century, rivets are used for permanent joints between plates of boiler shell, structural members of bridges and part of railway wagons and coaches. For making a riveted joint, a hole has to be drilled in the plate to be connected. Riveting is used in many applications, such as cold riveting of thin sheets, riveting sheets of aeroplane structures, etc. Riveting is much faster and also the cheapest process of producing a permanent joint. There are two types of riveted joints, butt joint and lap joint. A butt joint is that in which the main
plates are kept in alignment butting (i.e. touching) each other and a cover plate (i.e. strap) is placed either on one side or on both sides of the main plates. The cover plate is then riveted together with the main plates. The failures of riveted joint takes place by tearing of the plate, shearing of rivet and crushing of rivet and plate under the action of overloading. Hence the stress pattern in riveted butt joint by varying parameters like thickness of plate, linear pitch, transverse pitch and method of riveting is studied.
-
Introduction to Problem, Scope and Methodology
In this research riveted joints using different elements under static load conditions are analyzed. For this purpose single rivet double strap joint is considered under static loading conditions. Due to riveting process complex residual stress state is introduced for the riveted joint (both for the rivet and the plates). During the installation process the plates are pressed together by the deformed rivet. This causes surface contact stresses between the joined plates. The stresses are obtained analytically. Then a 3-D model is prepared in Pro-E software and its stress analysis is done by F.E.M. using ANSYS by varying parameter such as thickness of main plate (t), linear pitch (p) and transverse pitch (pt). Also the analysis is done for chain, diamond and zig-zag riveting using same number of rivets in each main plate. The experimental test model is prepared using aluminium alloy plate and rivet. The test is carried out in universal testing machine to determine shearing strength of rivet by applying tensile load on main plate. The plate and rivet are made up of aluminium alloy and its mechanical properties are tabulated in Table.1.
Table 1 Properties of Material
Modulus of Elasticity (Mpa)
E
71000
Poissons ratio
0.33
Density of material (Kg/mm3)
2.77e-006
-
Analytical Stress Analysis of Riveted Butt Joint
The analytical stress calculations for riveted butt joint are performed using following relations [1].
-
Tearing stress in a plate per pitch length t =
Stress concentration factor (kt = 2.35) is consider for the tearing of plate
2 2
2 2
-
Shearing stress on rivet =
4
-
Crushing stress on rivet and plate
c =
-
Maximum shear stress
Table 2 Finite element analysis results
Sr.
no.
Stress in single riveted double strap butt joint
F.E.A.
stresses
Analytical stresses
1
Tearing stress (t) in plate (Mpa)
276-390
322.02
2
Shear Stress () in rivet (Mpa)
11-70
67.85
3
Max. shear Stress (max) in rivet (Mpa)
53-102
96.52
4
Max.Principal Stress (1) in rivet (Mpa)
87-166
165.07
5
Von-mises stress (eq) in rivet (Mpa)
90-188
180.49
Fig. 1 Tearing stress contour on main plate with 3 mm thickness
max
= 1 [ t2 + 42
2
-
Maximum principal stress
= t + 1 [ t2 + 42 ]
1 2 2
-
Equivalent stress (Von-mises stress) eq = 2 + 32
-
-
Finite Element Analysis of Riveted Butt Joint
In this chapter, three-dimensional stress field solutions are obtained in the single riveted double strap joint geometric configuration under both the residual stress field and external tensile loading. Three-dimensional finite element models of riveted butt joints have been developed using a commercial finite element program ANSYS (Workbench). Nonlinearity arising from the interaction (frictional contact condition) between the rivet and Plates was incorporated in the model. The local stress state in a riveted butt joint is very complex due to the residual stress (clamping stress applied by rivet heads and radial pressure applied by rivet expansion) resulting from rivet installation process, surface shear within the contacting zone due to load transfer through friction, pin loading at hole due to load transfer through rivet shear, secondary bending effects of the joint, and biaxial tension in plates due to the applied tensile load.
Thus the results obtained from finite element analysis are shown in table 2 and fig. 1 to 5.
Fig.2. Shear stress contour on rivets with 3mm thickness of main plate
Fig.3. Maximum Shear stress contour on rivets with 3mm thickness of main plate
Fig.4. Maximum principal stress contour on rivets with 3mm thickness of plate
Fig.5. Von-mises stress contour on rivets with 3mm thickness of plate
-
Experimental Stress Analysis of Riveted Butt Joint
A single riveted butt joint as shown in fig.6 is considered for determination of shearing strength. A prototype of rivet joint is prepared and it is tested on universal testing machine (UTM). The photograph of experimentation is shown in fig.
7. And the shearing stress thus determined is 67.8 MPa.
Table 3 Observation between FEA and analytical values by varying thickness of main plate
SHEAR STRESS (N/MM2)
SHEAR STRESS (N/MM2)
|
Stresses in riveted butt joint ( MPa) |
FEA stresses |
Analytical stresses |
||||
|
Thickness of main plate (t) in mm |
Thickness of main plate (t)( mm) |
|||||
|
3 |
4 |
5 |
3 |
4 |
5 |
|
|
Tearing stress (t) |
280- 393 |
190- 290 |
171- 245 |
32 2 |
24 2 |
193 |
|
Shear Stress () |
10- 71 |
11- 71 |
11- 71 |
67 .8 |
67. 8 |
67.8 |
|
Max. shear Stress (max) |
56 108 |
56- 91 |
53- 90 |
97 |
85 |
79 |
|
Max.Princip al Stress (1) |
87 169 |
92- 157 |
85- 146 |
16 5 |
13 6 |
120 |
|
Von- mises stress(eq) |
112- 195 |
98- 163 |
94- 154 |
18 1 |
15 6 |
143 |
|
Stresses in riveted butt joint ( MPa) |
FEA stresses |
Analytical stresses |
||||
|
Thickness of main plate (t) in mm |
Thickness of main plate (t)( mm) |
|||||
|
3 |
4 |
5 |
3 |
4 |
5 |
|
|
Tearing stress (t) |
280- 393 |
190- 290 |
171- 245 |
32 2 |
24 2 |
193 |
|
Shear Stress () |
10- 71 |
11- 71 |
11- 71 |
67 .8 |
67. 8 |
67.8 |
|
Max. shear Stress (max) |
56 108 |
56- 91 |
53- 90 |
97 |
85 |
79 |
|
Max.Princip al Stress (1) |
87 169 |
92- 157 |
85- 146 |
16 5 |
13 6 |
120 |
|
Von- mises stress(eq) |
112- 195 |
98- 163 |
94- 154 |
18 1 |
15 6 |
143 |
72
70 analytical
68 value
F.E.A.value
66
3 4 5
THICKNESS (MM)
Fig.6 Dimension for test specimens
Fig. 7 Failure of test specimen
Fig. 8 Variation of shear stress w.r.t. thickness of main plate
3
4
THICKNESS (MM)
5
3
4
THICKNESS (MM)
5
600
400
200
0
600
400
200
0
F.E.Analys
F.E.Analys
is
is
Analytical
analysis
Analytical
analysis
TEARING STRESS (MPA)
TEARING STRESS (MPA)
Fig. 9 Variation of tearing stress (normal stress) in plate w.r.t. thickness of plate.
-
Results and Discussions
150
MAX. SHEAR STRESS
(Mpa)
MAX. SHEAR STRESS
(Mpa)
100
analyt ical
The comparison between finite element analysis and analytical analysis result are as shown
50 value
F.E.A.
in table 3 and fig.8 to 12.
0
3 4 5
THICKNESS (MM)
value
Fig. 10 Variation of maximum shear stress in rivet
w.r.t. thickness of main plate.
MAX. PRINCIPAL STRESS (Mpa)
MAX. PRINCIPAL STRESS (Mpa)
200
100
0
3
THICK
4 5
NESS (MM)
analytic al value F.E.A.
70
69
68
67
66
70
69
68
67
66
analytic
al value F.E.A.
value
analytic
al value F.E.A.
value
SHEAR STRESS (Mpa)
SHEAR STRESS (Mpa)
value
Fig.11 Variation of maximum principal stress in rivet w.r.t. thickness of main plate.
VOM-MISES STRESS (Mpa)
VOM-MISES STRESS (Mpa)
300
200
54
58
LINEAR PITCH (MM)
62
54
58
LINEAR PITCH (MM)
62
Fig. 13 Variation of shear stress w.r.t. linear pitch of rivet
100
0
3 4 5
THICKNESS (MM)
analytic
1000
500
0
1000
500
0
TEARING STRESS
(Mpa)
TEARING STRESS
(Mpa)
al value F.E.A.
analytical
value F.E.A.
value
analytical
value F.E.A.
value
value
Fig.12 Variation of von-mises stress in rivet w.r.t. thickness of main plate
From table 3 and fig. 8 to 12 it is observed that good agreement is obtained between analytical and
F.E.A results. The following observations are obtained.
-
From fig.8, it is observed that there is no effect of thickness of the main plate on shear stress in
54 58 62
LINEAR PITCH (MM)
54 58 62
LINEAR PITCH (MM)
Fig.14 Variation of tearing stress w.r.t. linear pitch of rivet
MAX.SHEAR STRESS
(Mpa)
MAX.SHEAR STRESS
(Mpa)
150
140
rivet.
130
analytical
-
From fig.9, it is observed that there is decrease in
120 value
normal stress (tearing stress) in plate with increase in thickness of main plate.
-
Fig.10 shows that there is decrease in maximum shear stress in rivet with increase in thickness of
110
100
54 58 62
L R P M)
F.E.A. value
main plate.
INEA ITCH (M
-
Similarly fig.11 and fig.12 depicts that decrease in maximum principal stress and von-mises stress in rivet with increase in thickness of main plate. Table 4 Observation between FE and analytical
analysis values by varying linear pitch of rivet
Fig.15 Variation of maximum shear stress w.r.t. linear pitch of rivet
MAX. PRINCIPAL STRESS (Mpa)
MAX. PRINCIPAL STRESS (Mpa)
300
Stresses in riveted butt joint(MPa)
FEA Values
Analytical Values
Linear Pitch of Rivet (p) in mm
Linear Pitch of Rivet (p) in mm
54
58
62
54
58
62
Tearing
514
528
415
stress(t) in
–
–
–
555
499
454
plate
670
670
531
Shear Stress () in rivet
17
69
13
– 6
9
69
66.8
66.8
66.
8
Max. shear Stress max) in rivet
78
139
65
128
61
120
135
125
117
Max.Princi
104
97
42
palStress
–
254
232
214
(1) in rivet
230
209
194
Von- mises
169
106
114
stress (eq)
–
–
–
263
242
225
in rivet
269
246
227
Stresses in riveted butt joint(MPa)
FEA Values
Analytical Values
Linear Pitch of Rivet (p) in mm
Linear Pitch of Rivet (p) in mm
54
58
62
54
58
62
Tearing
514
528
415
stress(t) in
–
–
–
555
499
454
plate
670
670
531
Shear Stress () in rivet
17
69
13
– 6
9
69
66.8
66.8
66.
8
Max. shear Stress max) in rivet
78
139
65
128
61
120
135
125
117
Max.Princi
104
97
42
pal Stress
–
254
232
214
(1) in rivet
230
209
194
Von- mises
169
106
114
stress (eq)
–
–
–
263
242
225
in rivet
269
246
227
200 analytical
value
100 F.E.A.
0 value
54 58 62
LINEAR PITCH (MM)
Fig. 16 Variation of maximum principal stress
300
250
300
250
VON-MISES STRESS
(Mpa)
VON-MISES STRESS
(Mpa)
w.r.t. linear pitch of rivet
analytical
value
analytical
value
LINEAR PITCH (MM)
LINEAR PITCH (MM)
200
200
54
54
58
58
62
62
Fig. 17 Variation of von-mises stress w.r.t. linear pitch of rivet
From the table 4 and fig 13 to fig.17, it is seen that
-
There is no effect of linear pitch of the rivet on the shear stress in the rivet.
-
There is decrease in tearing stress (normal stress) in the main plate with increase in linear pitch of rivet.
-
There is decrease in maximum principal stress, maximum shear stress and von-mises stress in rivet with increase in linear pitch of rivet.
-
Table 5 Observation between FE and analytical
70
SHEAR STRESS (Mpa)
SHEAR STRESS (Mpa)
69
68
67
66
65
18 20 22
TRANSVERSE PITCH (MM)
analytic al value
F.E.A.
value
analysis values by varying transverse pitch of rivet
Fig. 19 Variation of shear stress w.r.t. transverse pitch of rivet
140
138
136
134
132
analytical
value
140
138
136
134
132
analytical
value
TRANSVERSE PITCH (MM)
TRANSVERSE PITCH (MM)
18 20
18 20
22
22
F.E.A.
value
F.E.A.
value
MAX. SHEAR STRESS
(Mpa)
MAX. SHEAR STRESS
(Mpa)
Stresses in riveted butt joint (MPa)
FEA Values
Analytical Values
transverse Pitch of Rivet(p)in mm
transverse Pitch of Rivet (p) in mm
18
20
22
18
20
22
Tearing stress (t) in plate
514-
670
545-
690
544-
689
555
555
555
Shear Stress () in rivet
17
69
10-
69
4
69
66.8
66.8
66.8
Max.shear Stress (max) in rivet
78
139
72
139
70
139
135
135
135
Max.Principal Stress (1) in rivet
104-
230
94
230
101-
231
254
254
254
Von- mises stress (eq) in rivet
169-
269
149-
267
132-
264
263
263
263
Stresses in riveted butt joint (MPa)
FEA Values
Analytical Values
transverse Pitch of Rivet(p)in mm
transverse Pitch of Rivet (p) in mm
18
20
22
18
20
22
Tearing stress (t) in plate
514-
670
545-
690
544-
689
555
555
555
Shear Stress () in rivet
17
69
10-
69
4
69
66.8
66.8
66.8
Max.shear Stress (max) in rivet
78
139
72
139
70
139
135
135
135
Max.Principal Stress (1) in rivet
104-
230
94
230
101-
231
254
254
254
Von- mises stress (eq) in rivet
169-
269
149-
267
132-
264
263
263
263
Fig. 20 Variation of maximum shear stress w.r.t. transverse pitch of rivet
238
MAX.PRINCIPAL STRESS(MPa)
MAX.PRINCIPAL STRESS(MPa)
236
234
232
230
analytical value
228 F.E.A.valu
800
600
400
200
800
600
400
200
226 e
TEARING STRESS (Mpa)
TEARING STRESS (Mpa)
18 20 22
TRANSVERSE PITCH(MM)
0
analytical value
F.E.A.val ue
0
analytical value
F.E.A.val ue
18
20
22
18
20
22
TRANSVERSE PITCH (MM)
TRANSVERSE PITCH (MM)
Fig. 18 Variation of tearing stress w.r.t. transverse pitch of rivet
Fig. 21 Variation of maximum principal stress
268
266
264
262
260
268
266
264
262
260
analytical
value
anlytical
value
VON-MISES STRESS (Mpa)
VON-MISES STRESS (Mpa)
w.r.t. transverse pitch of rivet
F.E.A.
value
18
F.E.A.
value
18
20
20
22
22
TRANSVERSE PITCH (MM)
TRANSVERSE PITCH (MM)
Fig. 22 Variation of von-mises stress w.r.t. transverse pitch of rivet
From the table 4 and fig.18 to fig.22 it is observed that there is no effect of variation in transverse pitch on the stresses developed in main plate and rivet.
Table 5 Observation between FE and analytical analysis values by varying riveting method.
Stresse s in
riveted butt joint (MPa)
FEA Values
Analytical Values
Method reveting
of
Method reveting
of
Dia mon d rivet ing
Zig
-zag rive ting
Cha in rive ting
Dia mon d rivet ing
Zig zag rive ting
Cha in rive ting
Tearing stress (t) in plate
522
– 656
507
– 657
497
– 634
554.
9
634
.
555
Shear
Stress () in rivet
14
69
6
– 69
17
69
66.8
0
66.
8
66.
8
Max.
shear Stress (max)
60
– 141
97
– 154
78
139
135.
5
151
135
in rivet
Max.Pr
incipal
105
46
104
Stress (1) in
– 259
– 288
– 230
253.
5
285
254
rivet
Von-
mises stress (eq) in
149
– 297
183
– 298
169
– 269
262.
8
294
263
rivet
700
600
500
400
300
200
100
0
700
600
500
400
300
200
100
0
chain riveting
chain riveting
daimond rivetin
zig-zag riveting
daimond rivetin
zig-zag riveting
STRESS (Mpa)
STRESS (Mpa)
Fig.23 Variation of stresses w.r.t. method of riveting
From table 5 and fig.23 it is found that minimum stresses are induced in chain riveting as compared to other method of riveting. Hence the chain riveting produces 10 % to 11 % more safe joint as compared to diamond and zig-zag riveting.
-
-
Conclusion
The experimental determination of breaking strength of riveted butt joint revealed the shearing strength of rivet 8633 N (i.e. 67.85 MPa)
.The F.E analysis of riveted butt joint for same geometry revealed the shear stress of 70 MPa. This investigation confirmed that shearing stress in the rivet determined by experimentation and F.E. analyses are in close agreement. Analytical and
F.E. static stress analysis of riveted butt joint is performed by varying parameters like thickness of main plate, linear pitch of rivet, transverse pitch of rivet and method of riveting, from which it is revealed that the result obtained are in good agreement to each other. Looking at variation of von-mises stress with respect to thickness of main plate (t) and linear pitch (p) it is found that the stresses decreases with increase in value of these parameters. There is no effect of transverse pitch on the stress. Hence to have safe joint, it is better to increase the thickness of main plate and linear pitch instead of increase in transverse pitch. Also the analysis shows that von-mises stresses obtained in chain riveting are lesser as compared to diamond and zig-zag riveting. From this, it can be concluded that chain riveting is the most safe method of riveting.
-
References
-
Marin Sandu, Adriana Sandu, Dan Mihai Constantinescu.;Strength Of Adhesively Bonded Single-Strapped Joints Loaded In Tension, The Romanian Academy, Series A, Volume 11,No.4, Pg. 371379 (2010)
-
Essam A. Al-Bahkali.;Finite Element Modeling For Thermal Stresses Developed In Riveted And Rivet-Bonded Joints, International Journal Of Engineering & Technology IJET-IJENS, Vol: 11, No. 06 (2011)