Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes
The pivoting support is a core structure that assures rotation of super full-rotation cranes. The surface-surface sliding-friction pivoting support is a new potentiality, yet several technical problems still need to be solved, e.g., equilibrium between the pivoting support and tracks. The distributi...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2015
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| Назва видання: | Проблемы прочности |
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nasplib_isofts_kiev_ua-123456789-1732642025-02-09T14:05:23Z Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes Распределение контактных давлений между поворотной опорой и подкрановыми путями для кранов сверхвысокой производительности Guo, J.T. Li, S.F. Feng, L. Научно-технический раздел The pivoting support is a core structure that assures rotation of super full-rotation cranes. The surface-surface sliding-friction pivoting support is a new potentiality, yet several technical problems still need to be solved, e.g., equilibrium between the pivoting support and tracks. The distribution of contact pressures of three pivoting support models for four typical load cases was calculated. Analysis of contact pressures was based on the finite element method, and the distribution curves for circumferential contact pressures were plotted. The pivoting support design effect on the contact pressures is studied, demonstrating an optimum structure that provides for the contact pressures to be well distributed. Поворотная опора ключевая конструкция, обеспечивающая вращение полноповоротного крана сверхвысокой производительности. Конструкция поворотной опоры на контактных салазках трения скольжения открывает новые возможности, однако целый ряд технических проблем все еще нуждается в решении, в том числе равновесие между поворотной опорой и подкрановыми путями. Выполнен расчет распределения контактных давлений для трех моделей поворотной опоры и четырех типичных случаев нагружения. Анализ контактных давлений основан на методе конечных элементов, построены кривые распределения окружных контактных давлений. Изучено влияние конструкции поворотной опоры на контактные давления, предложена оптимальная конструкция, обеспечивающая равномерное распределение контактных давлений. 2015 Article Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes / J.T. Guo, S.F. Li, L. Feng // Проблемы прочности. — 2015. — № 1. — С. 68-73. — Бібліогр.: 11 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/173264 539.4 en Проблемы прочности application/pdf Інститут проблем міцності ім. Г.С. Писаренко НАН України |
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Научно-технический раздел Научно-технический раздел |
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Научно-технический раздел Научно-технический раздел Guo, J.T. Li, S.F. Feng, L. Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes Проблемы прочности |
| description |
The pivoting support is a core structure that assures rotation of super full-rotation cranes. The surface-surface sliding-friction pivoting support is a new potentiality, yet several technical problems still need to be solved, e.g., equilibrium between the pivoting support and tracks. The distribution of contact pressures of three pivoting support models for four typical load cases was calculated. Analysis of contact pressures was based on the finite element method, and the distribution curves for circumferential contact pressures were plotted. The pivoting support design effect on the contact pressures is studied, demonstrating an optimum structure that provides for the contact pressures to be well distributed. |
| format |
Article |
| author |
Guo, J.T. Li, S.F. Feng, L. |
| author_facet |
Guo, J.T. Li, S.F. Feng, L. |
| author_sort |
Guo, J.T. |
| title |
Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes |
| title_short |
Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes |
| title_full |
Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes |
| title_fullStr |
Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes |
| title_full_unstemmed |
Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes |
| title_sort |
distribution of contact pressures between the pivoting support and tracks for super cranes |
| publisher |
Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| publishDate |
2015 |
| topic_facet |
Научно-технический раздел |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/173264 |
| citation_txt |
Distribution of Contact Pressures between the Pivoting Support and Tracks for Super Cranes / J.T. Guo, S.F. Li, L. Feng // Проблемы прочности. — 2015. — № 1. — С. 68-73. — Бібліогр.: 11 назв. — англ. |
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Проблемы прочности |
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2025-11-26T15:40:27Z |
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| fulltext |
UDC 539.4
Distribution of Contact Pressures between the Pivoting Support and Tracks
for Super Cranes
J. T. Guo,
1
S. F. Li,
2
and L. Feng
3
School of Civil and Safety Engineering, Dalian Jiaotong University, Dalian, China
1 gjtan@djtu.edu.cn
2 lsf_910tonghua@163.com
3 805913500@qq.com
The pivoting support is a core structure that assures rotation of super full-rotation cranes. The
surface-surface sliding-friction pivoting support is a new potentiality, yet several technical problems
still need to be solved, e.g., equilibrium between the pivoting support and tracks. The distribution of
contact pressures of three pivoting support models for four typical load cases was calculated.
Analysis of contact pressures was based on the finite element method, and the distribution curves for
circumferential contact pressures were plotted. The pivoting support design effect on the contact
pressures is studied, demonstrating an optimum structure that provides for the contact pressures to be
well distributed.
Keywords: full-rotation crane, pivoting support, sliding friction, contact pressure.
Introduction. With the development of the off-shore oil drilling platforms, there is an
increasing demand for higher capacity off-shore cranes. Since 1963, many developed
countries have invested in research and development of higher capacity off-shore cranes.
For instance, Holland refitted oil tankers into crane vessels with a capacity of 150 ton.
More recently, the maximum carrying capacity of single-suspension-armed cranes has
reached 7000 ton. China has successfully debveloped non-revolving floating cranes [1, 2]
with load-bearing capacities of 1300 and 1600 ton, and full-rotation-non-self-propelled
floating cranes [3] with a load-bearing capacity of 4000 ton. In 2008, a full-rotation-self-
propelled marine crane [4] has successfully accomplished operations, which involved its
rotation by 360 degrees under the load of 7500 ton.
The pivoting support is one of the core mechanisms of full-rotation cranes, as it
supports the crane and assures its rotation. The pivoting support connects the arm shelf of
the crane to the lower section of the crane, bears loads from above the slewing platform of
cranes, and passes the loads to tracks to the bearing platform via its bottom. Thus, the form
of pivoting support has a dominant influence on the construction of the hoisting devices
above the slewing platform, the supporting tube below the slewing platform, and the design
of the slewing drive device.
There are two types of structural pivoting support devices; the bogie and the roller [5].
The traditional type of full-circle slewing cranes commonly utilizes the bogie support
device with equalizer beams, which are based on equilibrium; therefore, the crane is still
supported despite the size, a higher barycenter and a lower stability, when the crane load
increases, whereas the multi-support-track-type pivoting supports with no equalizer beams
have a compact structure, lower barycenter and better stability. Also, they are simpler to
manufacture and install. This type of pivoting support is widely used for large-sized,
full-rotation offshore platform cranes. With an increase in the crane load, the crane-load
moment increases, and stress in the rollers cause them to become unbalanced and
overloaded, which contributes to a lower hosting capacity.
The recent idea for sliding pivoting support implies a slewing mechanism of sliding
friction, with chutes instead of rollers and surface-to-surface contact pairs utilized between
© J. T. GUO, S. F. LI, L. FENG, 2015
68 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1
the settled tracks and the chutes set at the bottom of the front half of the pivoting support.
This type of support also has a more compact structure, a lower barycenter, a higher
stability, a larger bearing surface and a higher loading capacity. However, the pivoting
support is still under development, with many technical problems to be solved. That is, the
pivoting support mechanism has to bear axial and radial loads, overturning moment,
driving torques during rotation, friction between the tracks, and the combination of them
all. The loss of balance takes place during the distribution of pressures between the rotary
beams and the interface of the tracks, in both circumferential and radial directions. The loss
of balance unduced by the contact stresses always leads to the deformation of bearing
chutes, interference on the rotation performance of cranes, and causes serious wear and
abrasion, which impairs both the carrying capacity and the serving life of cranes.
Based on the literature used for this study, the numerical analysis method [6] is used
for analyzing contact stresses of the sliding-friction pivoting support, as well as that of the
pivoting supporting of 2 8000� ton off-shore crane. Within framework of this study,
analyses on the distribution of contact pressures of three kinds of pivoting support models
under four typical loading conditions are conducted. Curves depicting the relationship
between the contact pressures and the circumferential angle are plotted, with values
obtained from the edges of the sliding contact surface. The circumferential and radial
distributions of contact pressures between pivoting supports and tracks are discussed. The
effects of pivoting support on contact pressures are analyzed and a reasonable structuring
providing the optimal distribution of contact pressures is proposed.
1. Methods and Analysis.
1.1. Computational Model and Loading Conditions. Pivoting support mechanism
and Computational Model. The pivoting support structuring, as shown in Fig. 1, consists
of upper platform girders, supporting columns, and lower girders. There is a pair of hinge
lugs (on hinge spot A, in Fig. 1) on the rear spars of the platform girders, and 2 pairs of
hinge lugs on the upper front beam (on hinge spot B and C, in Fig. 1), which respectively
join the A-frame and boom with a hinge allowing a rotation at any angle in the amplitude
plane. The girder on the bottom of the pivoting support is subdivided into two parts. The
front half that contacts the surface of the tracks is called a rotary beam. A box structure on
the bottom bearing surface has two concentric chutes that correspond to the tracks on the
bearing platform, providing a sliding contact with the tracks. The rear half has the equalizer
beams, while for the two concentric chutes on the bearing platform a rolling wheel rack is
used to balance the overturning moment, which allows one to avoid capsizing, ultimately
achieving a full-circle rotation of the whole crane.
The supporting columns contact the platform girders, leaving the lower girders with a
sufficient room for pivoting support, and upwards pass loading. This study is dedicated to
three different kinds of supporting column structuring models, as shown in Fig. 1. Edge
supporting columns in model I are straighter and shorter in distance between the columns,
Fig. 1. Models of sliding-friction pivoting support: (a) model I; (b) model II; (c) model III.
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1 69
Distribution of Contact Pressures between the Pivoting Support ...
a b c
while the edge supporting columns in model II are leaner and wider between the columns.
Although distances in model III are the same with that of model II, there are additional
secondary girders in model III that form a pattern of a double-decker W.
Sliding-friction pivoting support is a box structure formed by welded plates, which is
sumulated by shell elements in the proposed finite element model. These elements elements
are placed with consideration of their physical locations and assigned the attributes
corresponding to the physical thickness of the simulated plates. The secondary part, a
non-load-bearing structure, uses mass elements to simulate the effect of the counterweight.
The tracks, which are settled on an off-shore platform, have a comparatively higher rigidity
and small deformation, and thus are reduced in the analysis to rigid bodies. However, the
rotary beam and the sliding surface are considered as elastic bodies, which make up a
rigid-flexible contact pair, in order to take into account their deformations. Several 3D
surface-to-surface contact elements are used to simulate the contact between the tracks and
the sliding surfaces of rotary beams.
1.2. Load Cases. At the primary designing stage, the rotation condition was not
considered yet, so only four typical load cases were analyzed, according to the lifting
performance curve of the full-rotation cranes of 8000 ton.
Load case 1 – the lower limit of working range of the full load (the hoisting capacity),
when pressure in the front beam hinge point (hinge spot C in Fig. 1) reaches its maximum
value.
Load case 2 – the hoisting load and the working range of the jib attain a certain level,
while pressure in the A-frame hinge point (hinge spot B in Fig. 1) reaches its maximum.
Load case 3 – the hoisting capacity, where the main jib has the maximum working
range while running.
Load case 4 – the limit of the range that the main jib reaches without any load.
The load case with a hoisting capacity of 8000 ton and a working range of 50 m was
considered as referenced. When calculating different load cases, according to the position
of the jib of the crane, the external forces were assumed to be applied in every hinge point
of the girders on the upper platform: FA in point A, FBy and FBx in point B, FCx and
FCy in point C (as shown in Fig. 1a). These forces were treated as concentrated loads
applied to the corresponding nodes of the finite element model.
Rigid-flexible contact parameters were assigned, in accordance with the research
literature [7–11]. Study on the contact relationship between the bearing chutes of sliding-
friction pivoting support devices and the platform tracks was performed by the finite
element method (FEM).
2. Results.
2.1. Pivoting Support and Distribution of Contact Stresses in Tracks. Contact
pressures between the bearing chutes and the platform tracks were calculated using FEM.
The distribution of contact pressure between the pivoting support and the tracks is plotted
in Fig. 2. It can be seen that there are differences between the contact pressures in the two
chutes, and there exists a loss of balance among contact pressures. The loss of balance is
proved by different squeezing levels between the sliding surfaces of the rotary beam and
the tracks, as well as by the formation of contact spots. In the contact spot areas, contact
pressures are high, whereas outside those areas they are lower. The tracks are arc-shaped,
and only part of them bear pressures within 120–130�, where they overlap with the rotary
beam of the front half of the pivoting support, while the pressures are lower or close to zero
in the other parts of the tracks. Thus, it is expedient to focus only on the overlapped areas,
when analyzing the contact pressures.
For simplicity, the contact pressures for the two edges of the outer chute and two
edges of the inner chute were obtained, and the pressure-angle distribution curves of each
edge were constructed. The edges are numbered from outer to inner ones, with the outer
edge of the outer chute as edge I, the inner edge of the outer chute as edge III, the outer
70 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1
J. T. Guo, S. F. Li, and L. Feng
edge of the inner chute as edge III, and the inner edge of the inner chute as edge IV, as
shown in Fig. 2.
Insofar as the pivoting support is a symmetrical structure, there always exists a
symmetrical surface under lifting condition if the rotation condition is not taken into
consideration. The stresses and deformations on pivoting support two sides are equal, as
well as the contact status of the tracks. Therefore it is observed from only one side of the
track, which is within 0–65�. A distribution curve of circumferential pressures on the
contact surfaces was constructed using their values at the inner and outer edges of the three
models under different loadings. Distribution curves of contact pressures of model I under
load case 1 are presented in Fig. 3. Distributions of other models and load cases, as they
have quite similar characteristics as those of model I, are omitted for brevity. Figure 4
shows contact pressure–angle curves of the edge of the outer chute (edge I) for three kinds
of models.
Figures 3 and 4 demonstrate that the contact pressure values of the outer edge of the
outer chute, as well as of the inner edge of the inner chute, are generally higher than those
of the track surface. The contact pressures are distributed in a wavy pattern, where
pressures reach their minimum value in the symmetry center of the pivoting support rotary
beam, while pressures on both ends reach their maximum. In model I, pressures manifest
stong fluctuations with the maximum values at the ends, yet model II provides nearly the
same distribution as model III.
Fig. 2. Diagram of contact pressures between pivoting support and tracks.
Fig. 3. Contact pressure–angle curves of the edges, model I under load case 1.
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1 71
Distribution of Contact Pressures between the Pivoting Support ...
2.2. Discussion. The contact pressures induced by the load that emerges when the
crane is running, appeared to be lower at the ends but higher in the middle, acting in hinge
spots B and C as centered forces (Fig. 4). The pressure then moves downwards along the
supporting columns, finally resulting in heavy loads at both ends of the rotary beam. In
model I, distances between the supporting columns were shorter, with the maximum
distance being at the ends of the beam and the minimum distance in the center of the beam
under the loads passing upwards to the rotary beam. In models II and III, distances between
the two main supporting points were longer, deviation load on the rotary beam shrunk, and
contact pressures gradually smoothed. Additional secondary beams were added in model
III. A high and well-distributed rigidity of the beams made it possible to balance the
contact pressures, but did not provide any further applications regarding more complex
structures.
The distribution of the contact pressures along the rotary beam is controlled by its
design features: it is a box structure consisting of welded plates, circumferential risers at the
both sides with a higher rigidity, as compared to that of the cavity of the inner part, which
causes high contact pressures at the outer edge (Fig. 3, edge I) and the inner edge of the
inner chute (edge IV). Between lateral and medial side plates of the rotary beam there are
diaphragm plates, while the distances between the diaphragm plates coincide with the
wave period (Fig. 4).
Conclusions. The calculation results obtained for three models and 4 load cases show
a regular pattern of distribution of contact pressures between the sliding surfaces of the
rotary beam and the tracks. The areas, where the maximum contact pressures occurred,
were found at the ends of the pivoting support rotary beam. By increasing the distances
between the front supporting columns of the pivoting support, the scatter can be reduced,
and the difference in contact pressures will decrease. In the rotary beam, contact pressures
at the outer edge of the outer chute, as well as at the inner edge of the inner chute, are
generally higher than those at the sliding surface. The latter stresses have a wavy
distribution pattern with the peaks corresponding to the positions of diaphragm plates and
troughs corresponding to the cavity position. The key to improving the equilibrium
characteristics of contact pressures between sliding surfaces of the pivoting support rotary
beam and the tracks is a rational arrangement of diaphragms of the rotary beam, and
settlement on the consistent match of rigidity of the rotary beam.
Fig. 4. Contact pressure–angle curves of edge I of three models for load case 1.
72 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1
J. T. Guo, S. F. Li, and L. Feng
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Received 20. 10. 2014
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