Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions
Three-dimensional finite element analysis is applied to verify mechanical behavior of spot welds for one, three and five spot welds under tensile and compressive loading conditions. The elastic-plastic stress distribution at edge of hot spot weld is used for strength calculations. To obtain ex...
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| Опубліковано в: : | Проблемы прочности |
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| Дата: | 2004 |
| Автори: | , , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
Інститут проблем міцності ім. Г.С. Писаренко НАН України
2004
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions / H. Adib, J. Jeong, G. Pluvinage // Проблемы прочности. — 2004. — № 4. — С. 31-45. — Бібліогр.: 23 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859517605833867264 |
|---|---|
| author | Adib, H. Jeong, J. Pluvinage, G. |
| author_facet | Adib, H. Jeong, J. Pluvinage, G. |
| citation_txt | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions / H. Adib, J. Jeong, G. Pluvinage // Проблемы прочности. — 2004. — № 4. — С. 31-45. — Бібліогр.: 23 назв. — англ. |
| collection | DSpace DC |
| container_title | Проблемы прочности |
| description | Three-dimensional finite element analysis is applied
to verify mechanical behavior of spot
welds for one, three and five spot welds under
tensile and compressive loading conditions.
The elastic-plastic stress distribution at edge of
hot spot weld is used for strength calculations.
To obtain exact and reliable results for finite element
analysis of spot welds, which are generally
very small relative to other dimensions,
sub-modeling technique is applied. The proposed
numerical calculation scheme allows one
to take into account the material parameters
and geometrical non-linearity effects related to
a gap between thin plates, buckling, etc. We
provide the analysis of elastic and elastoplastic
behavior of specimens with various configuration
of spot welds subjected to tensile and
compressive axial loads.
Выполнен трехмерный конечноэлементный анализ образцов с одним, тремя и пятью точечными
сварными швами при растяжении и сжатии. Для расчета на прочность используется
распределение упругопластических напряжений в корне точечного шва. Предложена
методика субмоделирования, позволяющая получить более точные результаты конечноэлементного
расчета точечных швов малых размеров. Схема численного расчета дает
возможность учитывать параметры материала и геометрические нелинейные эффекты,
обусловленные наличием зазора между тонкостенными пластинами, их выпучиванием и т.д.
Проанализировано упругое и упругопластическое поведение образцов с различной конфигурацией
сварных швов при нагружении растягивающими и сжимающими осевыми усилиями.
Виконано тривимірний скінченноелементний аналіз зразків з одним, трьома
та п’ятьма точковими зварними швами в умовах розтягу і стиску. Для
розрахунку на міцність використовується розподіл пружно-пластичних напружень
у корені точкового шва. Запропоновано методику субмоделювання,
що дозволяє отримати більш точні результати скінченноелементного розрахунку
точкових швів малих розмірів. Схема числового розрахунку дає
можливість враховувати параметри матеріалу і геометричні нелінійні ефекти,
зумовлені наявністю зазору між тонкостінними пластинами, їх випинанням
і т.п. Проаналізовано пружну і пружно-пластичну поведінку зразків
із різною конфігурацією зварних швів при навантаженні розтяжними і
стискальними осьовими зусиллями.
|
| first_indexed | 2025-11-25T20:46:31Z |
| format | Article |
| fulltext |
UDC 539.4
Three-Dimensional Finite Element Analysis of Tensile-Shear
Spot-Welded Joints in Tensile and Compressive Loading Conditions
H. Adib, J. Jeong, and G. Pluvinage
Laboratoire de Fiabilité Mécanique, Université de Metz-ENIM, Metz, France
УДК 539.4
Трехмерный конечноэлементный анализ точечных сварных
соединений в условиях растяжения и сжатия
X. Адиб, Ж. Ж еонг, Г. Плю винаж
Университет г. Мец, Франция
Выполнен трехмерный конечноэлементный анализ образцов с одним, тремя и пятью точеч
ными сварными швами при растяж ении и сжатии. Д ля расчета на прочность исполь
зуется распределение упругопластических напряжений в корне точечного шва. Предложена
методика субмоделирования, позволяющая получить более точные результаты конечно
элементного расчета точечных швов малых размеров. Схема численного расчета дает
возмож ность учитывать параметры материала и геометрические нелинейные эффекты,
обусловленные наличием зазора меж ду тонкостенными пластинами, их выпучиванием и т.д.
Проанализировано упругое и упругопластическое поведение образцов с различной конфигу
рацией сварных швов при нагружении растягивающими и сжимающими осевыми усилиями.
Ключевые слова : трехмерный конечноэлементный расчет, соединения с
точечной сваркой, методика конечноэлементного субмоделирования, тонкие
пластины, зазор, выпучивание.
Introduction. Spot welding is one of the most practical and reliable methods
for fixing thin metal sheets together. One of the desirable characteristics of spot
welding techniques is its application in robotization. Hence, spot welds are widely
applied to produce thin sheet components, especially in the automotive and
transport industries. Fatigue is one of the critical problems in the design of spot
welds. The required local stress and strain parameters in welded joints are
commonly obtained via calculation, measurements and experimental based results
[1]. The local stresses, in turn, induce stress concentration, which can be assessed
using plate or shell model assumptions. Alternatively, finite element methods
(FEM) are used for local stress-based fatigue prediction, e.g., using the Neuber
[2], the Molski-Glinka [3-4], the volumetric approach [5-6], etc.
Three-dimensional finite element (3D FEM) stress analysis is applied to the
most spot-welded joints, including tensile-shear, cross tension and peel-coal ones
[7-12]. In this study, elastic-plastic 3D FEM analysis is applied to modeling of
the mechanical behavior of mono point, triple points and multiple points in
tensile-shear spot welds. The gap effects between two thin sheets are accounted
for and compressive behavior of spot-welded joints is investigated.
© H. ADIB, J. JEONG, G. PLUVINAGE, 2004
ISSN 0556-171X. Проблемы прочности, 2004, № 4 31
H. Adib, J. Jeong, G. Pluvinage
To take into account spot welds, which are generally very small relative to
other dimensions of welded joints, the main problems are a small sheet thickness
and existence of stress concentration at the edges of nuggets, which are very
sensitive to geometrical dimensions of spot welds (i.e., nugget diameter, small
sheet thickness, etc.) To obtain exact and reliable distribution of the local stresses
and strains at spot welds in three-dimensional case is usually very difficult due to
a specific geometrical configuration of these spots. Hence, many assumptions
based on application of beam elements, shell elements and combination of these
two elements are proposed. For example, plate strip model, continuous beam
model, combination of shell and solid elements for thin plates and nuggets,
respectively [13], and application of a single beam [14] can be considered as the
most practical methods (Fig. 1 ).
The most reliable and exact methods for determination of stress distribution
in tensile shear spot welds are restricted to 3D FEM analyses.
Solid elements Plate elements
Clamped support
7
B e a m e le m e n t
C la m p e d su p p o rt
a
b
Shell e lement
Fig. 1. Finite-element models for a mono-point-spot-welded joint: (a) plate strip model for
tensile-shear spot welds; (b) continuous beam assumption; (c) application of shell, rigid bar, and
solid elements for tensile-shear spot welds; (d) beam and shell element in vertical direction.
32 ISSN 0556-171X. npoôneMU npoHHocmu, 2004, № 4
Three-Dimensional Finite Element Analysis
1. Finite Elem ent Model Description. We perform FEM analysis for three
specimen configurations involving a mono point, triple points, and multiple
points spot-welded joints (Fig. 2). Due to symmetry, only one-half of spot-welded
joints is considered. Solid elements with 20 nodes are used, and the ANSYS
software is applied for linear and nonlinearcalculations. One end of specimens is
fixed, while the other end is loaded in longitudinal direction of spot-welded joints
by tensile or compressive loads. FEM analysis takes into account the material and
geometrical nonlinear behavior of mono point spot-welded joint, which leads to
their large-scale rotation displacements in their deformed shapes [13]. For triple
and multiple point cases, the rotation phenomenon is less manifested, and thus the
geometrical non-linearities can be neglected.
Fig. 2. Geometrical configuration of mono point, triple points and multiple points tensile-shear
spot-welds left to right, respectively. (All dimensions are in mm.)
To obtain more realistic and reliable FEM analysis, it is critical to know the
actual material properties and behavior. The cyclic stress-strain curve, which
contains stiffening and hardening features of material, is very suitable for stress
calculation via FEM analysis. The stress-strain curve for the material under study
is shown in Fig. 3 [15].
Cyclic stress strain curve
A<J=J£'Aen
n - 0. 1 001
£ - 5 7 6 M Pa
U U . U U Z U . V U O U . U U O U.U1Ae
Fig. 3. Cyclic stress-strain curve and the material parameters: cyclic strain hardening exponent and
coefficient n' and K ', respectively.
ISSN 0556-171X. npoôëeMbi npounocmu, 2004, N 4 33
H. Adib, J. Jeong, G. Pluvinage
The material properties are: Young’s modulus E = 205,000 MPa, Poisson’s
ratio v = 0.28, yield stress o j = 299 MPa, and the ultimate stress o u = 431 MPa.
As seen from Fig. 2, the nugget is very small relative to the specimen length and
width. Therefore we use a sub-modeling technique, in order to obtain the local
stresses and strains at the nugget edge. In Fig. 4, the typical mesh and geometrical
dimensions of the spot weld incorporated into the sub-modeling method are
presented.
'I
2R
d
Fig. 4. General configuration of the FEM models: mono point (a), triple point (b), and multiple
point (c) spot-welded joints, and detailed view of the spot weld (d).
2. Application of Sub-M odeling M ethod in Spot-W elded Joints. The
sub-modeling technique overcomes the scale difference problems, discussed in
the prevoius sedction and thus makes possible to get more accurate results in the
required region of the FEM model. The cut boundaries for sub-modeling
technique are presented in Fig. 5. These should be located far enough from the
stress concentration zone, i.e., radii of the cutting boundaries for spot welds
should be twice higher than that of a nugget. Sub-modeling reduces, or even
eliminates, the need for sophisticated transition regions in solid FEM models and
34 ISSN 0556-171X. npo6n.eMH npounocmu, 2004, N 4
Three-Dimensional Finite Element Analysis
allows one to optimize mesh density of the required region. However, sub
modeling applications are restricted to solid element models and cut boundaries’
distances from the stress concentration zones. The cut boundaries need to be far
enough from the hot-point stress zones, otherwise considerable errors in FEM
results for considered models are likely to be obtained. Therefore, it is necessary
to provide the comarative analysis of stress distributions obtained for the cut
boundaries using the sub-model and the full-sized model and check the
calculation accuracy. The cut boundary planes for tensile-shear spot-welded joint
are shown in Fig. 5. The respective stresses calculated for the full-sized model
and sub-model with the above the cut boundaries are presented in Fig. 6 .
Symmetry plane
Fig. 5. The general configuration of cut boundary planes for tensile-shear spot-welded joint.
The comparative analysis of three tensile shear spot welds, including mono
point, triple points and multiple points (see Fig. 6 ) demonstrates that the
sub-model has a suitable accuracy and its cut boundaries are located far enough
either from the high level stress locations and the hot points. Hence, the
application of sub-modeling is expedient for the reliable analysis of the stress
concentration zone near the spot-weld edges.
3. Stress D istribution near Spot Welds in Tensile Shear Spot-Welded
Joints. The stress distribution for tensile shear spot-welded joints is the basis of
spot weld design. Figure 7a presents the basic diagram of spot weld stress
analysis: the stress values are given for left to right direction of spot welds.
Figure 7b shows the distribution in thickness direction of stresses, which are
generated as a combination of bending and tensile stresses at the edge of spot
welds.
The stress distribution in longitudinal direction of spot welds for three
tensile-shear spot welds, which is presented in Fig. 8 , can be subdivided into three
zones. Zone I covers the stress evolution in the lower plate, while zone II and
zone III correspond to the stress distributions in the nugget and upper plate,
respectively. The peak stress locations are at the end of zone I and at starting
point of zone III.
ISSN 0556-171X. npoôëeMbi npounocmu, 2004, N 4 35
H. Adib, J. Jeong, G. Pluvinage
150
125
100
75
50_
O ' *5
&
'0 0
( 0 -25
-50
-75
-100
-125
-150
b
\ Gît boundaries for Mono Spot Weld
LeSfnBigbi Hand 5 de
_______ ^ ftl^p d S d eJ | EtiglilHmd5dg____
- Sub-Model for Right Hand Side
“Full-Mode for Eight Hand Side
" Sub-Model for Left Hand Side
“Full-Model for Left Hand Side
“ Sub-Model for Left to Right Hand Side
“Full-Model foi Left to Right Hand Side
1 2 3 4
Nugget center distance (mm)
a
Cut boundaries for Triple Spot Welds
T txft ffi K igM Hanr! fiirTp
Left Hand Sirfel 1 Right HauiSids
- Sub-Model for Right Hand Side
-Ftdl-Mode for Right Hand Side
-Sub-Model for Left Hand Side
-Full-Model for Left Hand Side
- Sub-Model for Left to Right Hand Side
-Full-Model for Left to Right Hand Side
a—fr—a— -ft—&
2 3 4
Nugget center distance (m m )
Cut boundaries fcrMdtipie Spot Welds
^ taK i# tK n lS < fe
_____A a I a !
- Sub-Model for Right Hand Side
- Full-Mode for Right Hand Side
- Sub-Model for Left Hand Side
- Full-Model for Left Hand Side.
- Sub-Model for Left to Right Hand Side
- Full-Model for Left to Right Hand Side
0 1 2 3 4 5 6
Nugget center distance (mm)
Fig. 6 . Comparative analysis of elastic stress distributions calculated by the sub-model and
full-sized model for mono point (a), triple point (b), and multiple point (c) spot-welded joints.
b
36 ISSN 0556-171X. npoôneMbi npoHHocmu, 2004, № 4
Three-Dimensional Finite Element Analysis
i L Thickness
Fig. 7. The typical stress distribution near spot welds: (a) stress distribution in longitudinal direction
for upper plate and lower plate as anti-symmetric form; (b) stress distribution in plate thickness
direction (kt is elastic stress concentration factor, amax is the maximum stress, and ag is the net
stress).
-12 — 1-- 1--‘-- 1-- 1-- 1-- 1-- 1-- 1-- 1-- 1-- 1--‘-- 1-- 1— 1-- 1— 1-- 1-- 1--‘-- 1--‘—
0 1 2 3 4 5 6 7 8 9 10 11 12
Distance (mm)
Fig. 8 . Elastic stress concentration factor distribution near spot welds.
In Fig. 8 , three types of tensile-shear spot-welded joints are compared. The
elastic stress concentration factor k t has two tensile and two compressive peaks.
The comparative analysis of Fig. 8 reveals that triple points and multiple points
exhibit a similar mechanical behavior, whereas addition of two more spot welds
(multiple points) yields no high strength improvement as compared to triple
points. Moreover, stress values in the boundary condition at the edge of a spot
weld are less than the respective loads applied to the opposite side. Therefore,
failure always occurs from the side where the load is applied. The stress
distribution in thickness direction of thin plates is also critical. The initial cracks
are formed at the edge of spot welds. In plate thickness direction, stress evolution
depends on two major factors: 1) tension and 2) bending effects. The bending
stresses are generated because of eccentricity, which naturally exists in these
kinds of connections. Evidently, the tensile-shear spot-welded joints bending
stresses depends on the applied forces, sheet thickness and gap between two thin
plates. In Fig. 9, stress distribution in thickness direction is shown. High stress
values are formed at the edge of nugget, and the stresses change their sign to
negative at the neutral axis in plate thickness direction.
ISSN 0556-171X. npoôëeMbi npounocmu, 2004, N 4 37
H. Adib, J. Jeong, G. Pluvinage
Fig. 9. Elastic stress concentration factor evolution along plate thickness direction from inner side to
upper side for spot-welded joints.
Noteworthy is that the strength of spot welds plate thickness direction is
controlled by the gap between lower and upper plates. Insofar as the ratio
between the gap and the plate thickness is considerable even for a small gap, the
latter cannot be neglected in the stress analysis and design. Incorporation of gap
effects in FEM finite element models make a great difference in design of spot
welds. Figure 10 shows the gap effect for mono point tensile shear spot-welded
joint.
Fig. 10. The maximum structural stress evolution for elastic and elastic-plastic analysis due to gap
variation in mono spot-welded joint case (M = F (t + S) = Ft(1+ S/1)).
Hence, consideration of gap is essential for the estimation of fatigue strength
of tensile-shear spot welds, although it is neglected the most researchers, e.g.,
[8-12]. Incorporation of the gap parameter d in our 3D FEM analysis of
tensile-shear spot-welded joints has revealed that this effect is the most
pronounced in the case of mono spot-welded joint. In the current study the gap
value is 0 . 1 2 mm and all calculations are based on experimental observation of
selected specimens. As the stress distribution around spot welds is elastic-plastic,
the cyclic stress-strain curve is used for calculations. As seen from Fig. 11, the
stress relaxation in plastic zones near high stress location occurs, and a max
depends on the elastic-plastic stressed state.
38 ISSN 0556-171X. npoôëeMbi npounocmu, 2004, N 4
Three-Dimensional Finite Element Analysis
24
20
16
12Oft
\D
'"iS 8
E
Ü 4
II b
M 0
-4
-8
-12
— M o n o p o in t s p o t w e ld e d j o in t
—O — T r ip le p o in ts sp o t w e ld e d jo in t
- —£x— M u ltip le p o in ts s p o t w e ld e d jo in t
Zone I
. , , , ,
N u g g e t d ia m e te r / j
Zone I I
, , , ..........................
Zone I I I
Distance fnwi
Fig. 11. Fatigue stress factor elastic-plastic distribution near spot welds in longitudinal direction.
(The applied force for all spot-welded joints is taken as F = 2250 N.)
The elastic-plastic stress distribution in sheet thickness direction is given in
Fig. 12.
Fig. 12. Fatigue stress factor elastic-plastic distribution near spot welds in longitudinal direction.
(The applied force for all spot-welded joints is taken as F = 2250 N.)
Here the same pattern as in the elastic case is observed: There are peak
stresses as well, and tensile stresses change into compressive ones. However, in
the elastic-plastic case, the neutral axes of triple and multiple spots approximately
coincide, while mono spots are characterized by a larger tensile zone.
4. Compressive Loading Conditions for Tensile-Shear Spot-Welded
Joints. The spot welds are generally applied for connection of two thin plates.
Due to small thickness of these joints, their applicability is restricted to certain
specific cases. The mechanical behavior of tensile-shear spot-welded joints under
compressive loading conditions is critical for estimation of their application
range. However, mostly tensile loads are currently accounted for in the
application of spot welds (e.g., in automobile industry, for many types of thin
sheet connections). In operational conditions, compressive loads can be
experienced by spot-welded structures. Therefore, the buckling effect can occur in
ISSN 0556-171X. npoôëeMbi npounocmu, 2004, N 4 39
H. Adib, J. Jeong, G. Pluvinage
tensile-shear spot-welded joints. We took this effect into account in the present
3D FEM analysis. Due to similarity between fixed-fixed ends and all the joints
under study, this type of buckling is modeled in order to estimate that of
tensile-shear spot-welded joints (Fig. 13).
Fig. 13. Schematic representation of critical buckling load for fixed-fixed ends (L, b, and t are the
n 1EI n 1Ebti
plate length, width, and thickness, respectively; Pcr = r r x 1 = —~ i—).
(0.5L)2 3L2
It is evident from Fig. 14 that the first buckling mode is the most typical for
all three spot-welded joints under study.
Fig. 14. The first buckling mode configuration for mono point (a), triple point (b), and multiple
point (c) tensile-shear spot-welded joints.
The critical buckling loads for the three tensile-shear spot welds obtained
from the 3D FEM analysis using the ANSYS software are summarized in Table 1.
It is noteworthy that the critical buckling load for fixed-fixed ends can be easily
calculated using the available input data [16-17].
As seen from Table 1, all spot-welded joints under study have a higher
buckling resistance tant a plate with fixed-fixed end conditions, but the critical
buckling load capacity for triple points is the highest. The major parameter in
40 ISSN 0556-171X. npoôëeMbi npounocmu, 2004, N 4
Three-Dimensional Finite Element Analysis
buckling analysis is geometrical characteristics. The comparison between triple
and multiple points spot-welded joints in Fig. 2, indicates that the distance
between triple joints in longitudinal direction of spot-welded joint is two times
relative to multiple-points. Due to this geometrical effect, unbraced distance for
triple points is less than multiple points spot-welded joints. Hence, the major
geometrical parameter, which has a great effect in buckling capacity of spot welds
can easily be distinguished. Other parameters such as plate thickness, nugget
diameter and number of spot welds is also important to verify compressive
behavior of tensile-shear spot-welded joints, but the most effective geometrical
parameter in buckling capacity of spot welds is distance between spot welds or
unbraced distance. In Fig. 15, the braced and unbraced distances for buckling
capacity analysis are shown.
T a b l e 1
The Critical Buckling Load and Effective Length for Three Different Types
of Spot-Welded Joints
P N1 cr ’ 1
\n2EI
Spot-welded joint type KL — J , mm
V Pcr
K
Fixed-fixed ends 636.71 150.00 0.5000
Mono point 866.85 128.55 0.4285
Triple points 1203.92 190.08 0.3636
Multiple points 1025.59 118.18 0.3939
Fig. 15. Braced and un-braced length for three spot-welded joints (mono point, triple points, and
multiple point’s tensile-shear spot-welded joints).
The braced and unbraced distances are very important to manipulate
compressive behavior of spot-welded joints, and it is shown in Table 1 that the
number of spot welds improves the buckling capacity of tensile-shear spot-
welded joints, while the unbraced length augmentation results in a lower buckling
ISSN 0556-171X. npoôëeMbi npounocmu, 2004, N 4 41
H. Adib, J. Jeong, G. Pluvinage
capacity. Although multiple spot-welded joints have two additional spot welds,
their buckling capacity is less than that of triple ones. This can be attributed to
the unbraced and braced length effects. The distance between spot welds in
tensile behavior is also important, but manifests a different behavior pattern. The
braced length in all spot-welded joints provides a rigid section and if the braced
length is long, the rigid section increases, which require higher force values to
obtain the buckling conditions. Hence, the lowest buckling capacity can be
expected from mono point spot-welded joints. And the highest one - from lap
welded joint.
In addition to the buckling effect, we have studied the post-buckling
behavior of spot welds. The nonlinear buckling analysis is required to investigate
the post-buckling conditions of all three mentioned spot-welded joints. The
rotation of spot welds is the most critical parameter in their post-buckling
analysis. In Fig. 16, the post-buckling behavior of three selected spot-welded
joints is shown. Here the angle between two thin sheets (20) changes with the
compressive axial load.
2 5 0 0
''"'2000
o
o Ph
1500
a
j> 1QGG
06
0>
^ 500
o
O
0
0 1 2 3 4 5
0 , deg
Fig. 16. Post-buckling analysis of selected tensile-shear spot-welded joints with the same spot weld
configuration.
As seen from Fig. 16, the rotation of mono point spot-welded joint occurs
even at low compressive loads. Hence, joint rotation based on compressive loads
for mono spot-welded joints is more noticeable. The experimental results for
tensile-shear spot welds demostrate the same pattern [18]. The triple and multiple
points produce less pronounced joint rotation as compared to the mono points,
which can be related to the respective number of spot welds and their locations.
5. F ractu re M echanics Applicability to Spot-W elded Joints. The results
obtained from this study suggest that tensile-shear spot-welded joints exhibit
different mechanical behavior in tension and compression. The spot-welded joints
study can be subdivided into low-cycle fatigue (LCF) and high-cycle fatigue
(HCF). The crack initiation and propagation occur in the heat-affected zone
(HAZ) and base metal within the LCF and HCF ranges, respectively. Low axial
loads correspond to the HCF range and, consequently, cracks initiate and
propagate in the HAZ. Alternatively, high axial loads lead to initiation and
propagation of cracks in the base metal, which makes possible application of the
42 ISSN 0556-171X. npo6n.eMH npounocmu, 2004, N 4
Three-Dimensional Finite Element Analysis
fracture mechanics to tensile-shear spot-welded joints. Various formulas for the
stress intensity factors in such joints have been derived [19-21]. However, the
available fracture mechanics approaches and SIF formulas for spot-welded joints
are not applicable to crack initiation in the HAZ and for the LCF analysis
[22-23]. Therefore, the proposed elastic-plastic 3D FEM analysis can be used as a
tool of further expansion into this field.
C o n c l u s i o n s
1. Three-dimensional mechanical behavior of tensile-shear spot-welded
joints has been studied for three spot-welded joint types, including mono point,
triple points and multiple points. FEM solutions of stress fields in the spot welds
are obtained for elastic, elastic-plastic, buckling and post-buckling loading cases.
The application of sub-modeling technique yielded more accurate and less
time-consuming numerical results than conventional FEM meshing schemes.
2. The stress distributions near spot welds in longitudinal and thickness
directions have been analyzed, the critical point being the toe of spot welds. The
mono point case, due to its specific configuration and a large plastic zone,
exhibits a high joint rotation and a complex deformation pattern, while triple and
multiple points produce less joint rotation and are more preferable for application
from this standpoint.
3. The mechanical behavior of triple and multiple point spot-welded joints
are very close to each other in tension and compression. Hence, they have similar
strain and stress distributions, which suggest similar fatigue behavior. The stress
distribution in thickness direction reveals that a combination of the axial stresses
and bending stresses controls the stress distribution pattern and mechanical
behavior of the joints under study. The gap existing in spot welds raises the stress
concentration factor at the toe of spot welds. Low thickness of sheet metals has a
significant influence on the stress distribution at spot welds. The gap effect results
in a higher bending moment, and consequently, in higher tensile stresses and
larger plastic zones, which reduce the fatigue life and load-bearing capacity of
spot-welded joints.
4. The buckling capacity of spot-welded joints has been studied. The
comparison between the chosen specimens and fixed-fixed end beam shows that
the larger number of spot welds results in a higher buckling capacity of
spot-welded joints, but such factors as braced and unbraced length play their role
as well. Post-buckling behavior of spot-welded joints has also been studied and
explained within the framework of the proposed approach.
5. Finally, such parameters as the number of spot welds, spot-weld diameter,
plate thickness, distance between spot welds or braced distance and gap between
two thin sheets are shown to be crucial for the reliable design of spot-welded
joints. The special emphasis is made on the gap effects, which are neglected in
recent publications, but are shown to deteriorate the mechanical behavior for
spot-welded joints. Another aspect of this problem is development of an adequate
model of processes in the heat-affected zone for the low-cycle fatigue life
prediction of spot-welded joints.
ISSN 0556-171X. npoöxeMbi npounocmu, 2004, N 4 43
H. Adib, J. Jeong, G. Pluvinage
Р е з ю м е
Виконано тривимірний скінченноелементний аналіз зразків з одним, трьома
та п’ятьма точковими зварними швами в умовах розтягу і стиску. Для
розрахунку на міцність використовується розподіл пружно-пластичних на
пружень у корені точкового шва. Запропоновано методику субмоделювання,
що дозволяє отримати більш точні результати скінченноелементного роз
рахунку точкових швів малих розмірів. Схема числового розрахунку дає
можливість враховувати параметри матеріалу і геометричні нелінійні ефек
ти, зумовлені наявністю зазору між тонкостінними пластинами, їх випи
нанням і т.п. Проаналізовано пружну і пружно-пластичну поведінку зразків
із різною конфігурацією зварних швів при навантаженні розтяжними і
стискальними осьовими зусиллями.
1. D. Radaj, “Theory of forces and stresses in spot-welded overlap joints,”
Arch. Appl. Mech., 67, 22-34 (1996).
2. H. Neuber, Kerbspannungslehre, Springer-Verlag, Berlin (1958).
3. G. Molski and G. Glinka, “A method of elastic-plastic stress-strain
calculation at the notch roots,” Mat. Sci. Eng., 50, 93-100 (1981).
4. G. Glinka, “Energy density approach to calculation of inelastic stress-strain
near notches and crack,” Eng. Fract. Mech., 22, 485-508 (1985).
5. G. Qylafku, Z. Azari, N. Kadi, et al., “Application of a new model proposal
for fatigue life prediction on notches and key-seats,” Int. J. Fatigue, 21,
753-760 (1999).
6 . H. Adib and G. Pluvinage, “Theoretical and numerical aspects of volumetric
approach for fatigue life prediction in notched components,” Ibid, 25, No. 1,
67-76 (2003).
7. M. Fujimoto, N. Mori, and S. Sakuma, Stress Distribution Analysis o f
Spot-Welded Joints under Tension-Shear Load, International Institute of
Welding, III-721-82 (1982).
8 . T. Satoh, H. Abe, K. Nishikawa, and M. Morita, “A study on three
dimensional elastic-plastic stress analysis of spot-welded joint,” Proc. 4th
Int. Conf. on Fatigue and Fracture Thresholds (15-20 July, 1990), Honolulu
Hawaii.
9. D. Radaj, Z. Zhang, and W. Muhrmann, “Local stress parameters at the weld
spot of various specimens,” Eng. Fract. M ech, 35, No. 5, 933-951 (1990).
10. X. Deng, W. Chen, and G. Shi, “Three dimensional finite element analysis of
the mechanical behavior of spot welds,” Finite Elem. Anal. Design, 35,
17-39 (2000).
11. W. Chen and W. Deng, “Performance of shell elements in modeling
spot-welded joints,” Ibid, 35, 41-57 (2000).
12. H. Henryson and B. L. Josefson, “Fatigue crack initiation at spot welds
fracture mechanics or strain life approach?,” Proc. 7th Int. Fatigue Congress,
Fatigue 99 (1999), Vol. 2, pp. 1251-1256.
44 ISSN 0556-171X. Проблеми прочности, 2004, № 4
Three-Dimensional Finite Element Analysis
13. D. Radaj and S. Zhang, “Geometrically nonlinear behavior of spot-welded
joints in tensile and compressive shear loading,” Eng. Fract. M ech, 51, No. 1,
181-194 (1995).
14. Y. Zhang and D. Taylor, “Fatigue life prediction of spot-welded components,”
Proc. 7th Int. Fatigue Congress, Fatigue 99 (1999),Vol. 1, pp. 1175-1180.
15. H. Adib, J. Gilgert, and G. Pluvinage, “Fatigue life duration prediction for
welded spots by volumetric method,” Int. J. Fatigue, 26, No. 1, 81-94
(1004).
16. S. P. Thimoshenko and J. M. Gere, Theory o f Elastic Stability, Second
edition, McGraw-Hill, New York (1961).
17. W. F. Chen and E. M. Lui, “Structural stability,” in: Theory and
Implementation, Elsevier, New York (1987).
18. H. Adib, “The effect of geometry in spot-welded joints for fatigue life
prediction,” Internal Report of Laboratory for Reliability Mechanics, Metz
University, 18 July 1000.
19. D. J. Chang and R. Muki, “Stress distribution in a lap joint under tension
shear,” Int. J. Solid Struct., 10, No. 5, 503-517 (1974).
10. L. P. Pook, “Approximate stress intensity factors for spot and similar welds,”
NEL Report 588, National Engineering Laboratory, UK (1975).
11. J. F. Cooper and R. A. Smith, “Initial fatigue crack growth at spot welds,”
Proc. Int. Conf. on Fatigue Engineering Materails and Structures (1986),
Vol. 1, pp. 183-188.
11. H. Adib, PhD Thesis, University of Metz, France (1003).
13. N. Pan and S. Sheppard, “Spot welds life prediction with cyclic strain
range,” Int. J. Fatigue, 24, No. 5, 519-518 (1001).
Received 05. 09. 1003
ISSN 0556-171X. npoöneMbi npoHHoemu, 2004, № 4 45
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| id | nasplib_isofts_kiev_ua-123456789-47110 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0556-171X |
| language | English |
| last_indexed | 2025-11-25T20:46:31Z |
| publishDate | 2004 |
| publisher | Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| record_format | dspace |
| spelling | Adib, H. Jeong, J. Pluvinage, G. 2013-07-09T18:51:35Z 2013-07-09T18:51:35Z 2004 Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions / H. Adib, J. Jeong, G. Pluvinage // Проблемы прочности. — 2004. — № 4. — С. 31-45. — Бібліогр.: 23 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/47110 539.4 Three-dimensional finite element analysis is applied to verify mechanical behavior of spot welds for one, three and five spot welds under tensile and compressive loading conditions. The elastic-plastic stress distribution at edge of hot spot weld is used for strength calculations. To obtain exact and reliable results for finite element analysis of spot welds, which are generally very small relative to other dimensions, sub-modeling technique is applied. The proposed numerical calculation scheme allows one to take into account the material parameters and geometrical non-linearity effects related to a gap between thin plates, buckling, etc. We provide the analysis of elastic and elastoplastic behavior of specimens with various configuration of spot welds subjected to tensile and compressive axial loads. Выполнен трехмерный конечноэлементный анализ образцов с одним, тремя и пятью точечными сварными швами при растяжении и сжатии. Для расчета на прочность используется распределение упругопластических напряжений в корне точечного шва. Предложена методика субмоделирования, позволяющая получить более точные результаты конечноэлементного расчета точечных швов малых размеров. Схема численного расчета дает возможность учитывать параметры материала и геометрические нелинейные эффекты, обусловленные наличием зазора между тонкостенными пластинами, их выпучиванием и т.д. Проанализировано упругое и упругопластическое поведение образцов с различной конфигурацией сварных швов при нагружении растягивающими и сжимающими осевыми усилиями. Виконано тривимірний скінченноелементний аналіз зразків з одним, трьома та п’ятьма точковими зварними швами в умовах розтягу і стиску. Для розрахунку на міцність використовується розподіл пружно-пластичних напружень у корені точкового шва. Запропоновано методику субмоделювання, що дозволяє отримати більш точні результати скінченноелементного розрахунку точкових швів малих розмірів. Схема числового розрахунку дає можливість враховувати параметри матеріалу і геометричні нелінійні ефекти, зумовлені наявністю зазору між тонкостінними пластинами, їх випинанням і т.п. Проаналізовано пружну і пружно-пластичну поведінку зразків із різною конфігурацією зварних швів при навантаженні розтяжними і стискальними осьовими зусиллями. en Інститут проблем міцності ім. Г.С. Писаренко НАН України Проблемы прочности Научно-технический раздел Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions Трехмерный конечноэлементный анализ точечных сварных соединений в условиях растяжения и сжатия Article published earlier |
| spellingShingle | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions Adib, H. Jeong, J. Pluvinage, G. Научно-технический раздел |
| title | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions |
| title_alt | Трехмерный конечноэлементный анализ точечных сварных соединений в условиях растяжения и сжатия |
| title_full | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions |
| title_fullStr | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions |
| title_full_unstemmed | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions |
| title_short | Three-Dimensional Finite Element Analysis of Tensile-Shear Spot-Welded Joints in Tensile and Compressive Loading Conditions |
| title_sort | three-dimensional finite element analysis of tensile-shear spot-welded joints in tensile and compressive loading conditions |
| topic | Научно-технический раздел |
| topic_facet | Научно-технический раздел |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/47110 |
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