Industrial robots are used for high-precision tasks and in intensive production. One of the most reliable methods for monitoring robots’ work is vibrodiagnostics, which provides recommendations and ...maintenance procedures, and also serves as a reliable diagnostic method for determining the causes of industrial robot failures. Connection of robot and the supporting structure is very important and it affects on dynamic behavior of the robot. This paper presents the process of diagnosing dynamic condition of the structure with painting robots, after the failure of the robot motion reducer. To analyze the causes of the failure, a numerical-experimental analysis was performed, which included: static calculation, dynamic calculation, determining transfer function in frequency domain and reinforcement factors and measuring accelerations. Supporting structure has very low eigen-frequencies (3,5 to 9.5 Hz), it cannot accept inertial forces and large deformations and resonant behavior occur. Using FEM analysis is shown that the behavior of the structure is unfavorable because 20 eigen-oscillations had a frequency less than 17 Hz, and all are located in the robots’ working space. Determination of the transfer functions showed that the dynamic gain factor in all three directions of the excitation force is extremely large, while the corresponding frequencies are 5 ÷ 20 Hz. As a part of the experimental analysis, accelerations and displacements at the robots’ locations were measured. Accelerations exceed the standard acceptable limit. It was determined that the main problem was the rigidity of the supporting structure and maintenance omissions observed during the visual inspection. Only a partial and relatively quick repair was done on the structure, and it significantly decreased displacements of most critical zones (robots).
•The increase in load-bearing capacity of the FCF is dependent on the strength increase of the filling body.•The filling body restrains the lateral deformation of the coal pillar to increase its ...load-bearing capacity.•The load-bearing process of FCF has a distinct stage of transition between the primary and secondary load-bearing structures.•As the width of the coal pillar increases, the crack initiation gradually moves from the pillar to the filling body.
The continuous mining and filling cemented coal mining (CMCB) technology solves the problem of unbalanced mining and filling efficiency in the coal mining with lane-type cemented filling. In order to study the alternate bearing characteristics of the roof of the field under this process, it is divided into the coal pillar bearing area, co-bearing area, and the filling body bearing area. In order to further study the mechanical properties and failure characteristics of the composite load-bearing structure composed of the filling body - coal pillar - filling body (FCF) in the co-bearing area, the strength growth law of the FCF and its crack expansion law is revealed through the uniaxial compression test. And the primary and secondary load-bearing relationships between the coal pillar and the filling body were obtained by the digital image correlation (DIC) method and the static strain test. The influence of coal pillar width on the strength of the FCF is further revealed by establishing the PFC model. The results show that: increasing the strength of the filling body can improve the overall strength of the FCF both directly and indirectly; while the interaction between the filling body and the coal pillar is distributed as large in the middle and small at the ends, and increases significantly with the increase in the strength of the filling body; the cracks of the FCF appear first at the weak structural surface formed by the coal pillar and the filling body, and the coal pillar is the main load-bearing structure before the peak stress, and gradually transitions to the secondary load-bearing structure in the post-peak deformation stage. The test results can be used as a reference for the design of the width of the lane, the optimization of the mining process, and the proportioning of the filling slurry.
In this paper deriving of dynamical model of the load-bearing structure in form of a Trusses of the excavator with rotor is elaborated. Finite Element Methods and real working conditions are used to ...derive the dynamical model and to perform the local linearization of the dynamic elastic line for the structure of the load-bearing of the excavator with rotor. As carriers with continuous masses were treated the upper bearing structure of the Dynamical model and the truss levels. Finally, in accordance with the requirements of the problem, the degrees of freedom and the reference nodes are selected. The second stage of reduction, represents the final formation of the dynamical model of the load-bearing infrastructure, which however must be more accurate during the dynamic behaviour of the excavator with the rotor. The exposed work with the formation of the dynamic model of the Truss bearing structure, enables the concrete solution of the oscillations of the excavator with rotor. In addition, the model is of a universal character, respectively, can also be used during the formation of the dynamical model of truss carriers in general.
•Flexible concrete formwork is used as the roadside support of gob-side entry retention.•A new integrated supporting control technology is proposed in this study.•The action mechanisms of supporting ...measures for gob-side entry retention are clarified.•The integrated supporting control technology promotes the formation of dual gas channels.
According to the factors affecting the stability of the integral load-bearing structure of the surrounding rock of a retained gob-side entry, the load-bearing capacity of roadside supports with flexible concrete formwork is studied to propose a new integrated supporting control technology. This approach is based on a bolt and anchor cable support with a wire mesh for retaining the surrounding rock of a roadway. Moreover, the core of this technology involves roof bolts and steel beam supports with a steel–plastic wire mesh on the side of the gob beside the retained roadway, combined with the strengthening support of dual single props with upper and lower crossbars in the roadway. The roof-strata pre-stressed anchorage composite load-bearing structure, roadside flexible concrete formwork load-bearing structure, wire-mesh wall structure, solid coal wall load-bearing structure, and four-in-one load-bearing and stress-transferring control device in the retained roadway are formed in the surrounding rock of the retained roadway using integrated supporting control technology. Additionally, their supporting mechanisms are analyzed, and the corresponding construction technologies are clarified. Practical field results indicate that the integral load-bearing structure of the surrounding rock of the retained roadway formed by the integrated supporting control technology effectively controls the deformation and destruction of the surrounding rock, ensuring the success of the retaining roadway. Furthermore, dual gas channels are successfully constructed using this technology, thereby validating its efficient gas extraction.
Prvok is the first 3D printed concrete floating house in the Czech republic. Additive manufacturing - 3D printing became a synonym of sustainable building of the 21st century. Its experimental manner ...and lack of world's standardisation ISO approvals hold the 3D printing concrete method on the edge of usability and applicability and stop a broader spread of application in practice. Furthermore, the used material was newly developed cement composite prefabricated mixture mady by Master Builder Solutions with polypropylene plastic micro-fibres, which was not previously tested in large structures. What we achieved, was a practical realisation of a 3D printed fully equipped and functioning concrete house as a habitable statue for a public event. In order to fulfil the request on insulation and avoiding heat bridges together with investing least material possible, we parametrically designed and implemented a wall system of construction. In order to be able to open the structure to the public, we tested it on the universal loading machines at the Faculty of civil engineering CTU Prague in scale 1:1. Testing fragments of the walls were also part of the research goals, which led us to the final design. In this paper, we present the results of the experiment together with the experimentally obtained data.
In response to the technical challenges of supporting tunnels in loose and fragmented surrounding rock with poor anchorage, strong dynamic pressure, and strong structural stress influences, extensive ...on-site surveys were conducted, and several typical problems of large deformation in coal mine tunnel surrounding rock and difficulty in rock control were summarized and analyzed. Based on the analysis of existing support technologies and theoretical foundations, a concept and method for the rapid support technology of reconstructing high-strength load-bearing structures were proposed. Taking the 11205 down-hill transport tunnel at Longbao Coal Mine in Guizhou as an engineering background, the causes of deformation and failure were analyzed. A combined support method of displacement and unloading for fragmented surrounding rock was designed in practice. The design plan and optimal parameter calculations for the roadside backfill wall were carried out, and a mechanical model for the load-bearing capacity of the ro
Purpose. The work is aimed to investigate the loading of load-bearing structure with composite material roof. This will allow reducing the dead weight of the hopper car and will contribute to the ...possibility of increasing its carrying capacity. Methodology. Investigations were performed using the example of hoper car for grain transporting, model 19-6869, manufactured by Karpaty Experimental Mechanical Plant. It is important to say that the use of composite material reduces the roof weight by up to 40% in comparison with the metal design. That is why mathematical modeling of dynamic loading of the hopper car with composite roof was carried out. Differential equations were solved by Runge-Kutta method in MathCad software package. Initial conditions were assumed to be zero. During the calculations, the spring suspension parameters of the 18-100 bogie models were taken into account. The obtained results of calculations were used when determining the main indicators of the roof strength. The spatial model of the hopper car roof was created in SolidWorks software complex. Calculation was performed by the finite element method, which is implemented in the SolidWorks Simulation (CosmosWorks) software complex. When constructing the finite element model of the hopper car, the isoparametric tetrahedra were used. The optimum number of the model elements was determined by the grapho-analytical method. Findings. The basic indices of load-bearing structure dynamics of hopper car with composite roof were obtained. Acceleration of the body in the mass center was 5,0 m/s2. Coefficient of vertical dynamics is equal to 0.67. It was found that the maximum equivalent stresses in the roof for all the considered loading schemes do not exceed the admissible values, that is, the roof strength is ensured. Originality. The mathematical modeling of dynamic loading of the load-bearing structure of the hopper car with composite roof was carried out. The acceleration values as the components of dynamic loading acting on it during operation as well as vertical dynamics coefficient were determined. The strength indicators of the composite roof under the main operational loading modes have been found out. Practical value. The conducted research will contribute to the creation of guidelines for the design of innovative structures of the rolling stock, as well as increase the efficiency of its operation.
Мета. У роботі передбачено дослідити навантаження несучої конструкції вагона-хопера з дахом із композитного матеріалу. Це дозволить зменшити тару вагона-хопера та сприятиме збільшенню його вантажопідйомності. Методика. Дослідження проведено на прикладі вагона-хопера для перевезення зерна моделі 19–6869 виробництва ДМЗ «Карпати». Важливо, що використання композитного матеріалу сприяє зменшенню маси даху майже на 40 % порівняно з металевою конструкцією. Тому проведено математичне моделювання динамічного навантаження вагона-хопера з дахом із композитного матеріалу. Розв’язок диференціальних рівнянь здійснено за методом Рунге–Кутти в програмному комплексі MathCad. Початкові умови взято рівними нулю. Для проведення розрахунків узято параметри ресорного підвішування візків моделі 18–100. Отримані результати розрахунків використано під час визначення основних показників міцності даху. Просторову модель даху вагона-хопера створено в середовищі програмного комплексу SolidWorks. Розрахунок здійснено за методом скінченних елементів, який реалізовано в програмному комплексі SolidWorks Simulation (CosmosWorks). Для побудови скінченно-елементної моделі даху вагона-хопера використано ізопараметричні тетраедри. Оптимальну кількість елементів моделі визначено за графоаналітичним методом. Результати. Отримано основні показники динаміки несучої конструкції вагона-хопера з дахом із композиту. Прискорення кузова в центрі мас склало 5,0 м/с2. Коефіцієнт вертикальної динаміки дорівнює 0,67. Установлено, що максимальні еквівалентні напруження в даху за всіх розглянутих схем навантаження не перевищують допустимих значень, тобто міцність даху забезпечується. Наукова новизна. Проведено математичне моделювання динамічного навантаження несучої конструкції вагона-хопера з дахом із композиту. Визначено уточнені величини прискорень як складові динамічного навантаження, що діють на нього в експлуатації, а також коефіцієнт вертикальної динаміки. Установлено показники міцності даху з композиту за основних експлуатаційних режимів навантаження. Практична значимість. Проведені дослідження сприятимуть проєктуванню інноваційних конструкцій рухомого складу, а також підвищенню ефективності його експлуатації.
The article presents the results of determining the dynamic loading of a tank wagon with malleable links between the pot and the frame. This solution will help to reduce the loading of the ...load-bearing structure of a tank wagon in the vertical plane. Mathematical modelling of the dynamic loading of the load-bearing structure of a tank wagon was carried out. As a prototype, the tank wagon of model 15-1443-06 was selected, with the actual dimensions of structural components recorded during field studies. It was established that the accelerations acting on the pot of the tank wagon were about 2.6 m/s2. The fields of distribution of accelerations relative to the load-bearing structure of the tank wagon were determined. The discrepancy between the results of computer and mathematical modelling was about 8%. The coefficient of fatigue strength reserve of the load-bearing structure of the tank wagon was calculated. The results of the calculation showed that the coefficient of fatigue resistance is 15% higher than permissible. The conducted research will help to reduce the loading of the load-bearing structures of tank wagons during operational modes, extend the life and safety of their operation, reduce maintenance costs, as well as create recommendations for the design of innovative structures.
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