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Analysis of threaded connections under impact load
To cite this article: K Talaka and D Wojtkowiak 2020 IOP Conf. Ser.: Mater. Sci. Eng. 776 012052
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
Analysis of threaded connections under impact load
K Talaśka and D Wojtkowiak
Chair of Basics of Machine Design, Poznan University of Technology,
Piotrowo 3 street, 61-138 Poznań, Poland
E-mail: krzysztof.talaska@put.poznan.pl
Abstract. Threaded connections are widely employed in machine construction as fasteners, most
often under static loads, but can also occasionally come under impulse or impact load. The latter
type of load is particularly dangerous for this type of components. The paper presents MES
analysis of a threaded connection under impulse load. The analysis takes into account thread
geometry and axial force load. The material for the connection elements was modeled as elastic
material. The work presents 2D models usable for determining the stress on components under
static load together with 3D models utilized for determining the state of stress in components
under dynamic loads (impact, impulse).
1. Introduction
Threaded connections are among the most commonly used in machine building. They serve an important
function, especially when it is necessary form an inseparable connection and very often they are used in
the construction of research stands [1–15]. Generally, there are two main recognized groups of such
connections. The ones used as connectors (under static or dynamic load) as well as the so-called screw
mechanisms used as transmission for converting rotational motion into linear motion and the other way
around. Depending on application, different thread geometries are used. The most commonly used one
are: triangular (metric and inch), trapezoidal (symmetrical and asymmetrical), square, rounded
trapezoidal, round etc. Threaded connections subject to the most extreme loads are found in the mining
and petrochemical industry, railroad industry, cranes (in particular in crane hook connections).
Interestingly, in some applications we observe different types of threads performing a similar function.
The earlier mentioned crane hook connection would serve as an example. For each hook size, depending
on manufacturer, we observe metric triangular threads (compliant with ISO 724) or triangular
trapezoidal thread (knuckle thread compliant with DIN 405 as well as the PN-83/M-84550 Polish
standard used earlier). Figure 1 presents the outline of both threads together with baseline dimensions.
Scientific research of threads have been carried out for decades. The main goal of the research effort is
to determine the influence of thread geometry on the load bearing capacity of the connection, the
influence of the thread profile on the phenomenon of indentation (actual state of surface after
processing), the evaluation of the effectiveness of selected assemblies in the aspect of decoupling
protection. The main motivation for taking up the research presented in this paper was to evaluate the
condition of stress in threaded coupling components under variable forces in a short time. The examined
time of variance was comparable to the propagation time of deformation waves in steel. The research
utilized the Abaqus Explicit software.
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
a)
b)
Figure 1. Thread profile geometry utilized in crane hook connections: a) triangular
tread – ISO 724, b) knuckle thread – DIN 405, PN-83/M-84550 [16].
2. Methodology of the research
Two tread types were subject to examination: M100x6 (ISO 724) and TrZ100x12 (PN-83/M-84550).
The connections were subject to loads in the range 0–700 kN (proof load – 70 tons). The height of the
nut was equal to the external diameter of the thread. Both the nut and the bolt were assigned
characteristics of alloy steel 34CrNiMo6. The examination was divided into two stages. In the first stage,
a simplified axisymmetric model was developed to evaluate the stress in both components under static
load. In the second stage, 3D models of treads were developed and used to evaluate the stress in material
of both components under highly variable forces (figure 2).
a)
b)
Figure 2. Thread models used in the analyses (TrZ100x12): a) axisymmetric 2D, b) 3D.
Figure 3 presents the method of load application on connections utilized in both models. The
axisymmetric model was subject to forces equal to 200 kN, 400 kN and 700 kN, whereas the 3D model
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
was subject to loads in range of 0–700 kN (figure 3 presents examples of force variance). Discretization
was carried out in such a manner which allows to accurately and exactly represent the outline of the
thread moreover, the finite element dimensions of the 3D model are identical to the finite elements in
the axisymmetric model.
a)
b)
Load: 200 kN, 400 kN, 700 kN
Figure 3. The method of applying load to the thread used in analyses (TrZ100x12):
a) axisymmetric 2D, b) 3D.
3. Results of the FEM analyses
Figures 4–6 present the distribution of von Mises equivalent stress and component S22 for both threads
and three loads (using the axisymmetric model).
a)
b)
Figure 4. Distribution of equivalent stress (Mises) and stress component
(S22) – under 200 kN load: a) TrZ100x12 thread, b) M100x6 thread.
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
a)
b)
Figure 5. Distribution of equivalent stress (Mises) and stress component
(S22) – under 400 kN load: a) TrZ100x12 thread, b) M100x6 thread.
a)
b)
Figure 6. Distribution of equivalent stress (Mises) and stress component
(S22) – under 700 kN load: a) TrZ100x12 thread, b) M100x6 thread.
Figures 7 and 8 present equivalent stress distribution for selected time limits, the graph line of the load
together with the stress values S22 is provided in selected area of the thread (lower lap of the screw
thread), for both threads – case 1. Figures 9 and 10 demonstrate the graph lines for load forces applied
to the connection together with maximum values of stress S22 for both threads, for load cases 2 and 3.
Figures 11 and 12 demonstrate examples of reduced stress for selected time limits; moreover, the graph
line of the load and the value of stress S22 were presented at the selected point of the thread (lower lap
of the screw thread), for both threads – case 4.
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
b)
a)
d)
c)
e)
d)
b)
a)
c)
e)
Figure 7. Distribution of equivalent stress (Mises) for selected time limits (M100x6):
a, b, c, d, e, the graph line of the load according to time and maximum values of stress
S22 – case 1.
b)
a)
c)
Figure 8.
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
d)
e)
d)
b)
a)
c)
e)
Figure 8. Distribution of equivalent stress (Mises) for selected time limits (TrZ100x12): a, b,
c, d, e, graph line of the load according to time and maximum values of stress S22 – case 1.
Figure 9. Graph line of the load as a function of time and maximum values of stress
S22 – case 2.
Figure 10. Graph line of the load as a function of time and maximum values of stress
S22 – case 3.
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
a)
b)
c)
d)
e)
f)
h)
g)
a)
h)
c) e)
f)
b)
d)
g)
Figure 11. The distribution of equivalent stress (Mises) for selected time limits (M100x6):
a, b, c, d, e, f, g, h, graph line of the load as a function of time with maximum stress value
S22 – case 4.
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
a)
b)
c)
d)
e)
f)
h)
g)
a)
h)
c) e)
f)
b)
d)
g)
Figure 12. The distribution of equivalent stress (Mises) for selected time limits (TrZ100x12):
a, b, c, d, e, f, g, h, graph line of the load as a function of time with maximum stress value
S22 – case 4.
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MMS2019
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 776 (2020) 012052 doi:10.1088/1757-899X/776/1/012052
4. Conclusion
The methodology presented in this study may be utilized for determining the stress state in threaded
connections under extreme loads that are variable in time. Two approaches were presented. The first,
simplified approach entailed the development of an axisymmetric model. It may be successfully
employed to determine the stress condition in materials of components in threaded couplings. However,
we may determine the stress value for a single, predefined load value. The presented 3D models can be
used to determine the state of stress under highly variable loads.
In the fourth load case, the changes in force value are so fast that the deformation waves propagate
at a similar speed in the material. This causes a phenomenon of wave superposition and concentration
of stress (time: 0.0002–0.0003 s) in the fourth load case. The presented models should be used for
analyzing threaded connections under impulse loads, in particular to avoid situations of deformation
wave superposition in the material during use.
5. References
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[16] Standards: ISO 724, DIN 405, PN-83/M-84550
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