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International Journal of Research In Science & Engineering
Volume: 1 Issue: 3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
FINITE ELEMENT ANALYSIS OF SCARF LAP RIVETED AND WELDED
JOINT WITH DIFFERENT LAP ANGLE
Nitisha K. Achmelwar
Student (ME Cad/Cam), Mechanical Engineering, JCOET, [email protected]
ABSTRACT
Load bearing capacity and fatigue tests will be carried out between Scarf lap riveted joint and Scarf lap welded
joint with different lap angle. Both experimental and computational studies are to be done and the results will be
validate The fabrication of the Scarf lap riveted joint and scarf lap welded joint will be done and tested on
Universal Testing Machine (UTM) after that the Finite Element Analysis with ANSYS will be done. After
introducing the lap angle between the faying surfaces the fatigue test and load bearing of joint will be seen.
There may be possibility of increasing the fatigue life and the joints may be reliable for the structure designs. The
objectives of this project is to compare simple lap riveted and welded joints with scarf lap riveted and welded
joints introducing with different lap angles and to find best suitable joint among scarf lap rivet and scarf lap weld
on the basis of analysis.
Keywords: Scarf lap riveted joint, Scarf lap welded joint, Lap angle, Simple lap riveted joint, Simple lap welded
joint.
----------------------------------------------------------------------------------------------------------------------------1. INTRODUCTION
Many researches focus on regular lap joint those are commonly used in fuselage and airfoil. In this paper
review we are introducing the scarf lap joint with different lap angle which is introduced into faying surfaces which
is rarely have been seen and reported. Various researches have been done on the scarf lap joint with different lap
angle on its fatigue performance, for the structures but the design of details and fatigue performance are not readily
available in literature. The Scarf lap joint is advantageous over the other lap joints. The important feature of Scarf
lap joint is the lap angle, which has the influence on its fatigue performance also it is effective in load transfer.
Consequently stress concentration reduced remarkably.
The experiments of joints have been studied by many scholars they proposed the joints with various tests.
There they have studied and investigated the fatigue and fracture behaviour for Scarf lap joint with different lap
angle. In previous studies it was found that the author has predicted the results with Smith Watson Method (SWT)
and Wang Brown Method (WB) have structure reliability in designs. The SWT method was achieving better
accuracy.
In this review paper we are introducing riveted as well as welded Scarf lap joint for testing with different
lap angle. Here we are suppose to analyse the Scarf lap joint in both manner i.e. Scarf lap riveted joint and Scarf lap
welded joint with different lap angle comparing it with Simple lap riveted joint and simple lap welded joint
performing by experimental and computational method. The main objective is to analyse best suitable Scarf lap
riveted joint and Scarf lap welded joint. Experimental testing on Universal testing Machine (UTM) and
computational analysis by ANSYS.
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International Journal of Research In Science & Engineering
Volume: 1 Issue: 3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
1.1 Riveted lap joint
A riveted lap joint is a permanent joint which uses rivets to fasten two materials. A rivet is a structure that
has a hemispherical head on one side and a cylindrical shaft on the other. Made from Aluminium alloys, steel, or
CRES and other special metals like titanium, nickel, and etc.There are some braw backs: Skilled workers required.
Leakage may be a problem for this type of joints, but this is overcome by special techniques.
Fig: Riveted lap joint
1.2 Welded lap joint
Metals can be generally joined using the welding technique – although there are some exceptions, but
almost any metal material (aluminium, carbon steel, stainless steel, tungsten) has a variation that is suitable for
welding. Welding is a type of permanent joint. There are some drawbacks: uneven heating and cooling during
fabrication so members get distorted or additional stress may develop. The inspection of welding is more difficult. It
required highly skilled labour and supervision.
1.
Fig: Welded lap joint
1.3 Scarf lap joint
Scarf lap joint is a joint in which two structural members are joined with long end laps and secured with
bolts, straps, keys, fishplates, etc., to resist tension or compression. A scarf lap joint may also be used to fix
problems caused when a board is cut too short for the application. The board can be cut in half with a tapered cut
yielding a scarf joint. When the joint is glued together, the tapers are slid against each other so that the two sections
are no longer in line with each other. This has the effect of making the board longer. Once the glue has set, the board
can be planed down to an even thickness, resulting in a longer but thinner board.
Fig: Scarf lap joint
2. SPECIMEN AND TEST SETUP
The geometry of six types of the scarfed lap joint illustrated in figure below including 6 mm-thick
specimens with different lap angle. Each of two specimens will have same angle so that one specimen will be of
riveted joint and one of welded joint. The assembled specimen for riveted joint the rivets used is countersunk rivets.
The jointed sheets and the rivets which are used are of MS Plate material.
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International Journal of Research In Science & Engineering
Volume: 1 Issue: 3
Sr No.
Joint
Type
Lap
Angle
(α)
Overlapping
Length
1
Scarf
lap
Riveted
joint
α=
2.93
l =117 mm
2
Scarf
lap
Riveted
joint
α=
3.81
l =90 mm
3
Scarf
lap
Riveted
joint
α=
5.44
l =63 mm
4
Scarf
lap
Welded
joint
α=
2.93
l =117 mm
5
Scarf
lap
Welded
joint
α=
3.81
l =90 mm
6
Scarf
lap
Welded
joint
α=
5.44
l =63 mm
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e-ISSN: 2394-8299
p-ISSN: 2394-8280
Design
International Journal of Research In Science & Engineering
Volume: 1 Issue: 3
Sr No.
Joint
Type
Lap
Angle
(α)
Overlapping
Length
7
Simple
lap
Riveted
joint
-
l =117 mm
8
Simple
lap
Riveted
joint
-
9
Simple
lap
Riveted
joint
-
l =63 mm
10
Simple
lap
Welded
joint
-
l =117 mm
11
Simple
lap
Welded
joint
-
l =90 mm
12
Simple
lap
Welded
joint
-
l =63 mm
e-ISSN: 2394-8299
p-ISSN: 2394-8280
Design
l =90 mm
These above geometries will be compared with each welded and riveted joints and will be found out the
best suitable joint. All specimen joints will be tested on Universal testing machine (UTM).
IJRISE| www.ijrise.org|[email protected] [80-85]
International Journal of Research In Science & Engineering
Volume: 1 Issue: 3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
3. FORMULATION
i. Tensile Stress
ii. Shear Stress
iii. Compression Stress
Maximum Principle Stresses
Maximum Shear Stress
√
Maximum Tensile Stress
√
Maximum Compressive Stress
√
4. ANALYSIS
1. Experimental and analytical investigation of fatigue and fracture behaviours for scarfed lap riveted joints
With different lap angle by X. Yuan ⇑ , Z.F. Yue, W.Z. Yan, S.F. Wen, L. Li from Advanced Material Test Centre,
School of Mechanics, Department of Engineering Mechanics, North-western Polytechnic University, Xi’an 710129,
China Fastener load-transferred experiments and fatigue tests of the scarfed lap riveted joints with different lap
angle were carried out. The fracture surfaces were observed by optical mic roscope (OM) in this paper. Both
experimental and computational studies were described and compared when possible. Based on the qualitative finite
element analysis (FEA), the multi-axial fatigue life of the scarfed lap riveted joints has been predicted by Smith–
Watson–Topper (SWT) method and Wang–Brown (WB) method respectively. Both of the test results and predicted
results show that fatigue life of scarfed lap riveted joints is remarkably increased after introducing lap angle into the
faying surface. 8 mm-thick specimens with the lap angle of 1.68 _C exhibit the best fatigue performance, and20
mm-thick with the lap angle of 3.37 _C do in the present study. Compared with the result of WB theory, the result of
SWT theory is more conservative and reliable. For structures ‘reliability designs, SWT theory and WB theory are all
fallibility.
IJRISE| www.ijrise.org|[email protected] [80-85]
International Journal of Research In Science & Engineering
Volume: 1 Issue: 3
e-ISSN: 2394-8299
p-ISSN: 2394-8280
2. Scarf Joint Angle Optimization by Samuel J. Noone from University of New South Wales at the
Australian Defence Force Academy The repair of composite structures is typically by scarf joint design. The current
scarf angle used in composite airframes is between 1 degree and 3 degrees. When the composite structure thickness
increases the repair size quickly becomes excessively large and inefficient. This project is continuation research in
the development and better understanding of the changes in scarf angle of joint size and load transfer efficiency
improvements. Through the use of theoretical, physical and finite element analysis it was found that by simply
changing the geometry, the stress concentration in the joint are not directly affected and that it is more dependent on
the residual stress provided from the steeper angle; the steeper angle being demonstrated to fail first due to the
higher peak stresses it attracts.
After studying both the above analysis we are performing the analysis based on riveted joint as well as
welded joint for scarf lap joint. Also we introducing the angle more as 1 to 3 . Experimental Analysis consists of
fabrication of scarf lap welded, riveted joint of MS flat plate. Stress and strength simple lap welded and rivet joint
and scarf lap welded and riveted joint will be find by using universal testing machine. Computational analysis by
using ANSYS will be done and it will comprise of stresses, buckling and vibration analysis .Result of experimental
and computational analysis will be svalidated.
5. CONCLUSION
On the basis of experimental analysis as well as by Finite Element Analysis we can observe by testing
1.
2.
3.
The strength of scarf lap joint over simple lap joint in the critical approaches.
Lap angle is an important factor for load transfer also for stress evolution.
Among the Scarf lap riveted joint and Scarf lap welded joint we will come to know the feasibility for
the application according to the strength with respect to lap angle.
6. REFERENCES
[1] X. Yuan, Z.F. Yue, W.Z. Yan, S.F. Wen, L. Li has carried out the Experimental and analytical investigation of
fatigue and fracture behaviours for scarfed lap riveted joints with different lap angle.
[2] Scarf Joint Angle Optimization by Samuel J. Noone from University of New South Wales at the Australian
Defence Force Academy The repair of composite structures
[3] Park Chul Young, Grandt Jr Alten F. Effect of load transfer on the cracking behaviour at countersunk fastener
hole. Int J Fatigue 2007; 29:146–57.
[4] Lijuan Liao, Toshiyuki Sawa , Chenguang Huang a Key Laboratory for Mechanics in Fluid Solid Coupling
Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing has done Numerical analysis on loadbearing capacity and damage of scarf joints subjected to combined loadings of tension and bending.
[5] Young w. Kwon Douglas Loup have the thesis on scarf joint modelling and analysis of composite materials
the objective of this study is to investigate joint strength of the scarf joint configuration with different material
combinations tested under various loading conditions like tension, compression, bending and shear loading.
[6] Young W. Kwon Naval Postgraduate School USA has studied about Strength of Composite Scarf Joints.
[7] C. H. Wang and A. Gunnion studied the Design Methodology for Scarf Repairs to Composite Structures Scarf
repairs are the preferred method of repairing thick composite structures, especially when externally bonde d
patches can no longer meet the stiffness, strength, and flushness requirements.
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