Design and Strength Analysis of a New Construction of a Sweeper with an Independent Surface Copying System Dedicated to Small Loaders and Front Loaders

Most enterprises and farms have paved parking lots, yards, warehouses, or sidewalks that need to be cleaned or cleaned. There are many sweepers available on the Polish and European markets, but there is still a lack of a solution that would be mounted on pallet forks and would have an independent copying system to support sweeping surfaces with different inclinations. The aim of the work was to develop a conceptual design for a new sweeper equipped with an independent surface copying system dedicated to small loaders and front loaders, as a well as strength analysis of the main frame. The conceptual design included an analysis of available solutions, development of a 3D CAD model of the new sweeper, and a detailed strength analysis of the sweeper’s main frame using the finite element method (FEM). The sweeper model was made in the Autodesk Inventor program, while the FEM strength analysis was made in the Siemens NX program. The designed frame model did not have nodes in which the stresses would be greater than 25% of the allowable stress in the material structure and 33% of the maximum allowable stress in the structure of the joints. The sweeper developed new design fulfills all the assumed functions and has a good chance of application.


Introduction
Currently, most enterprises and farms have paved parking lots, courtyards, warehouses, or sidewalks.Having the right equipment to clean these surfaces, usually made of paving stones, is a major investment.Of course, you can clean these surfaces manually with a broom, but it is a long-term and very tiring activity and the cleaning worker is exposed to a lot of dust in the air [1].Sweepers are perfect replacements for a traditional broom, especially in the fall and winter seasons.The problem of dust accumulation also occurs on the floors of workshops and warehouses, which creates many occupational hazards.If an employee wants to work efficiently and without worrying about his health, the workplace should be free from dust, etc. Workshop and warehouses can also be done with a broom, but the use of sweepers can minimize human effort [2].Modern models of sweepers are also used in gardens.Specially designed brushes are perfect for removing leaves, stones, sand, or dust, both in small and very large areas.Currently used sweepers are ergonomic and user-friendly.When cleaning, you do not have to bend down and collect the accumulated dust because in most sweeper designs, the collected dust is deposited directly into a container specially built into the sweeper's structure [3].Furthermore, modern sweepers allow you to clean sidewalks, streets, entrances, and industrial surfaces 5 times faster than manual sweep, but there are still no devices that allow the cleaning of surfaces with various reliefs (inclined surfaces).In summary, nowadays more and more emphasis is placed on the cleanliness of squares, car parks, and industrial areas, although these surfaces often have various relief terrains (they are sloping, they have planned slopes to drain rainwater).Sweepers can also be used to harvest agricultural produce, such as almonds.California is the world's largest producer and exporter of almonds.Currently, the sweeping of almonds during harvest produces significant amounts of dust, which causes air pollution in adjacent urban areas [4].
Cleaning streets, squares, or public spaces allows one to maintain the proper condition of the environment, as well as increases the standard of living of the inhabitants.Sweepers help to maintain the quality of ambient air standards within the allowed rang.There are many road sweepers available on the Polish and European market, but there is still no solution that would be mounted on pallet forks and would have an independent copying system supporting the sweeping of surfaces with various inclinations (inclined car parks, warehouses, factory roads, sidewalks).
Therefore, the purpose of the work is to design a sweeper mounted on pallet forks with an independent copying system and a strength analysis of the main frame dedicated to attaching to small loaders and front loaders locked to tractors.
Currently, when designing new machines and devices for strength analysis, the finite element method (FEM) is used the most.This method has been and is used to analyze displacement, kinematics, statics, and even dynamics [5].This method has also been used successfully to find the location of mechanical damage and the location of damage to perforated materials.Data from the literature also indicate that FEM is used to search for energy-saving production processes for dry ice compaction (agglomeration) [6] and to reconstruct random kinematic excitation of the road based on dynamic responses of vehicle suspension [7].
This method was also used to simulate fracture of the cortical structure of human bone [8], stress analysis of 3D prints [9], and the construction of orthopedic orthoses using additive manufacturing methods [10].During the literature review, the work using the finite element method was used to analyze the stresses of the front loading structure, as well as the resistance to abrasion of polymer concrete surfaces [11].Due to the repeatability and acceptable error of the FEM method compared to the actual stresses, it was also used for strength analysis in this work.

Material and research methods
The supporting frame of the new sweeper design is made up of steel profiles.These profiles are connected to joints.The dirt tank and the screen that covers the brush and other elements that are not an integral part of the sweeper's structure are attached to the frame.Standard strength rules were used to calculate the strength of the frame and determine the stresses that occur in it.These rules are based on the hypothesis of the highest straight strain energy (Huber-Misses_Hencky hypothesis) [12].The following assumption was made (1): (1) where: • Re -the yield point of the material (235 MPa), • x -the arbitrary factor of safety.
The safety factor was used because it is impossible to precisely determine all possible loads on the structure, the materials are not perfectly homogeneous, the calculation methods are characterized by a certain error and the manufacturing technology is exposed to inaccuracies.For this reason, based on the experience of the research team and the analysis of the scientific literature, the following safety factor values were adopted.
Hence, after rounding: kaccept_material = 196 MPa, kaccept_weld = 147 MPa.The sweeper construction model with an independent system for copying surfaces dedicated to small loaders and front loaders was designed in Autodesk Inventor Professional 2023.Then, a mesh was made to fill the space with finite elements.The result is that three-dimensional elements of a second-degree pyramid with additional nodes between the vertices are created.This ensures the best possible representation of the analyzed structure.Finite element method (FEM) calculations were performed using the Siemens NX program.When preparing the design of a new sweeper construction, in order to make its operation easier, it was decided to use terrain copying independent of a small loader or front loader.The boundary conditions were as follows: a) fix the frame in four points under the water tank, b) loading the structure with three pairs of forces.
The first pair of forces came from a full dirt tank with a capacity of 60, giving two forces of 600N each.The second pair of forces came from the brush mass with the hydraulic drive system and the sprinkler system and amounted to 500 N each.The third pair of forces came from the mass of the main frame and the mass of the jockey wheels and brush cover and amounted to 400N each.In total, the entire frame of the new sweeper design with the dirt tank was loaded with forces of 3000 N. A 3D CAD model of the new sweeper design with an independent surface copying system dedicated to small loaders and front loaders with a description of individual elements is presented in Fig. 1.

Figure 1.
Model view of a new sweeper with a dirt tank dedicated to small loaders and front loaders: 1-liquid tank, 2 -mechanism preventing the forks from slipping off, 3 -main frame, 4-hydraulic cylinder of the emptying mechanism, 5 -tank for dirt with the third jockey wheel, 6-hydraulic brush drive motor, 7 -jockey wheel, 8 -side brush, 9 -liquid pump, 10 -brush cover, 11-third jockey wheel.

Results
Strength tests were performed in the PLM Siemens NX 8.5 program.This program has previously been used by others to develop 3D models and analyze the strength of various elements of machines and marine vessels or to examine the root of the human aorta [13].Figure 2 shows the Von Misses reduced stress analysis, which shows that the most stressed nodes occur in the areas marked with red arrows, which amount to 48 MPa after rounding.Figure 3 shows an enlarged view of the reduced Von Misses stresses in the sweeper frame.Due to this, it can be seen that the greatest stresses occur at the point of connecting profiles or where welds are used (also marked with red arrows).The new design of the sweeper dedicated to small loaders and front loaders will reduce the costs of cleaning sidewalks, streets, entrances, and yards using existing equipment (small loaders and front loaders).Cleaning streets and sidewalks helps to maintain the appropriate condition of the environment and also improves the standard of living of residents.Half a century earlier, the profession of a road sweeper was known, while research conducted in Ethiopia showed that 98% of those working in this profession were usually dissatisfied with dusty conditions and intolerance of passersby [14], therefore it is justified to work on new designs of sweepers, especially those that increase functionality expensive equipment owned by small enterprises or farms (small loaders or front loaders).

Conclusion
The strength analysis performed using the finite element method (FEM) allowed the conclusion that the innovative design of the sweeper with an independent surface copying system dedicated to small enterprises or farms meets the strength assumptions (2,3,4): The test results and the method used are consistent with the results obtained and the method used by Truty et al. [15] in their work on the strength of the press adaptation table.This method was also used by Konecki et al. [16] in their work, the objective of which was to analyze the strength of selected elements of the bicycle body, allowing the selection of the most appropriate materials and the determination of compact dimensions.The stresses in the 3D frame model developed and analyzed amounted to a maximum of 47.97 MPa, which is only 25% of the allowable stresses of the material structure and 33% of the allowable stresses of the weld structures.Based on these results, it was concluded that the structure of the main frame of the sweeper with an independent surface copying system is not susceptible to deformation and is characterized by acceptable stiffness, with a 3-fold margin.This makes it possible to reduce the weight of the frame by implementing sheets, beams, and profiles with smaller cross sections and strength indicators, thus reducing construction costs.The next stage should be to make a prototype of a sweeper with an independent surface copying system, and then conduct a strain gauge test.This will allow you to verify the results obtained using the FEM method.The new design of the sweeper with an independent surface copying system fulfills the intended functions.To develop the design of the sweeper and improve its working conditions, further work should focus on a dust-reducing sprinkler system.

Figure 2 .Figure 3 .
Figure 2. Strength analysis of the main frame of the new sweeper with a dirt tank