Methodology Proposal, Virtual Simulations and 3D Printed Prototype of a Car Steering Wheel

Abstract

The design and production of car steering wheel prototypes have evolved significantly with advancements in virtual and additive manufacturing technologies. This study presents a comprehensive methodology for the development of a car steering wheel prototype, integrating theoretical analysis, virtual simulations, and 3D printing. Initially, material characteristics are defined to ensure structural integrity and suitability for automotive use. Stress-strain simulations in a 3D virtual environment validate the mechanical feasibility and functional properties of the prototype. The methodology further includes criteria for selecting 3D printers based on material compatibility, build volume, and aesthetic requirements, such as color options. Finally, the study incorporates experimental testing of standardized samples, including compression and hardness tests, to verify the mechanical properties and deformation behavior under load. This integrated approach aims to streamline the prototype development process while ensuring precision, reliability, and customization.

1. Introduction

Prototype development is a process that primarily takes place in software programs in a 3D virtual space. There is a connection between the design and virtual analyses, the purpose of which is to verify the required mechanical properties of a given prototype. Only after their verification is the actual production and physical testing carried out.

3D CAD (computer-aided design) software is an integral part of the design. The development of CAD applications is constantly being improved and adapted to the requirements that are subject to designers on the one hand and designers on the other. CAD applications, whether parametric or explicit, are still incorporating a variety of functionality requirements based on the requirements of their clients to satisfy old clients and attract the widest possible number of new users. They even develop common platforms for the use of parametric functionalities with explicit ones, and thus, 3D modelling takes on a new dimension [1,2,3,4].

The virtual world of 3D construction is currently increasingly realized through 3D printing [5,6,7,8,9,10]. Frequently used materials are plastics (ABS—Acrylonitrile Butadiene Styrene and PLA—Polylactic acid), gypsum composite, photopolymer, polyamide, resin, wax, ceramics, paper, metal (steel, brass, silver, bronze, gold or titanium), but also proteins, carbohydrates, and sugars used in 3D printing of food or even cells in 3D printing of biological tissue [11,12,13,14,15,16,17,18,19,20,21].

The main goal of companies that develop 3D printing and printers is to print the most accurate virtual model possible into a real form. Many 3D printers are able to print virtual model files modified and simplified into mostly STL (stereolithography) format, where, of course, there are inaccuracies. 3D printer software programmers also work with companies that program 3D CAD applications. Many 3D CAD applications are already able to send their virtual model directly to print without further modification of shapes and file formats. 3D printing is very efficient because the process is automated, and one printer can print a number of products in different shapes. Production efficiency is increasing, and final production costs are decreasing.

The number and different material compositions of usable materials in 3D printing are very extensive and are constantly growing. Products that are manufactured in this way are used in the commercial sphere. It is necessary to undergo appropriate tests of mechanical properties in order to verify their strength, durability, resistance to the required environmental influences, etc.

Many industries use 3D printing for the production of components that are considered small-series or customized. For example, many car companies offer consumers the opportunity to customize their vehicles with customized components [22,23,24,25,26,27,28]. Their production through 3D printing is relatively fast and allows car manufacturers to reduce delivery times and production costs for small-volume parts and custom production. This is partly because the technology eliminates the need to create individual tooling for each customized element, which would be financially impractical.

The aim of the work is to propose a methodology for creating a prototype of a virtual model of a passenger car steering wheel and then to test its mechanical properties. The main points are theoretical knowledge of the issue, defining material characteristics, and performing stress-strain simulations that will confirm the desired properties of the prototype. The following is a selection of suitable 3D printers according to the required materials, the dimensions of the printer’s working areas, and last but not least, the color options of the printing materials. The testing part is also important, where standardized samples will be subjected to compression and hardness tests in order to verify the required mechanical properties with deformation tests.

2. Methodology of Vehicle Steering Wheel Simulations

The proposal for a solution to this issue is based on the development of innovative technologies. These must be taken into account when creating a methodology according to the above specifications of the research problem. It is necessary to describe the individual steps: defining the input quantities, virtual simulations, 3D printing of the prototype, and verification of its mechanical properties.

The methodology of creation according to the above specifications of the research problem has been divided into 4 phases, with each phase having individual subphases:

• preparatory stage;
• virtual simulation phase;
• prototype 3D printing phase;
• test phase.

2.1. Preparatory Stage

In the preparatory phase, it is necessary to set partial goals that will bring concrete results in the later implementation phase, i.e., to make the prototype of the device feasible in practice. The preparatory phase is divided into the following subphases:

• 3D virtual model source data;
• defining material characteristics.

2.1.1. 3D Virtual Model Source Data

The source virtual 3D data is an assembly model of the car steering wheel, which consists of 7 parts. It is a 3D model of the steering wheel assembly, which can be customized according to the customer’s requirements. The model was modeled using the Creo Parametric 10.0 software application. This is one of the parametric CAD programs that enables feature-based modeling and preserves the complete tree of the history (model tree) of the 3D model. History allows for the retroactive modification of any element. The exploded state of the 3D model of the assembly is in Figure 1.

2.1.2. Defining Material Characteristics

An important subphase is the selection of a suitable material or several materials from which the individual parts of the assembly will be printed using 3D printing technology. When selecting suitable materials, it is necessary to define the individual requirements that must be met in order for the new prototype to meet the following requirements:

• Material strength

The steering wheel is part of the car’s control unit and is subjected to a strength test many times in the event of an accident. In a head-on collision, the driver of the car exerts his own weight on various places on the steering wheel, which must withstand the load of both the strapped and unrestrained driver. It is, therefore, very important that the steering wheel material is sufficiently resistant to unexpectedly high loads.

• UV stability

Many cars are not garaged and are constantly exposed to sunlight. The selected materials must be resistant to sunlight and must not degrade their properties under its influence, such as strength and color fastness.

• Resistance to high and low temperatures

The interior temperature of a car can reach up to 30 degrees Celsius higher than the outside temperature in summer, especially if it is a black car. When it is a mild 35 degrees outside, it can be a deadly 65 degrees inside, while the steering wheel and dashboard, which are black and absorb heat, can be even twenty degrees warmer, the total temperature reaches up to 85 degrees Celsius, where there is already a risk of skin burns when hands touch such a surface. Also, during the winter, there is a dramatic cooling in non-garaged cars. The selected material should be able to withstand temperatures in the range of −60 °C to +110 °C.

• Color variability

The solution will include colorful personalized elements that will complement the interior of the car according to the customer’s requirements. The development of various materials for 3D printers is unstoppable, but it is possible that the material that would meet all the previous requirements will not be in the desired color variations. In this case, it is possible to use different color shades of additional spraying.

After examining the material characteristics of the available 3D printer cartridges [29] and other detailed data sheets, the following materials meet the required criteria:

1.

Material: ABS-M30 (Acrylonitrile Butadiene Styrene—Thermoplastic Copolymer)

The M-30 type is 25 to 75% stronger than conventional ABS (depending on the manufacturer). It has suitable mechanical properties and is ideal for the production of functional models, prototypes, fixtures, and tools. It perfectly resists low and high temperatures, and its partial deformation is observed from +98 °C. It shows high resistance to UV radiation.

2.

Material: PC-ABS (Polycarbonate and Acrylonitrile Butadiene Styrene—Thermoplastic Composite)

This type of material combines the advantages of PC and ABS, and it is characterized by a very good ratio of functionality and machinability. The mixture of polycarbonate and ABS shows a synergistic effect, which results in excellent strength and impact resistance even at low temperatures, which is even better than the impact resistance of ABS or PC alone. It perfectly resists low temperatures and high temperatures up to +125 °C.

3.

Material: ASA (Acrylonitrile-Styrene-Acrylic—Thermoplastic)

The material is characterized by excellent UV resistance, good mechanical resistance, rigidity, and resistance to high temperatures. Other benefits include easy workability on 3D printers, print quality even with demanding details for small objects, excellent layering of the printed object, excellent weather resistance, and preservation of physical properties.

2.2. Virtual Simulation Phase

Simulations will be carried out using CAE (Computer Aided Engineering) applications. These are based on the principle of the Finite Element Method (FEM), where the investigated area of complex geometry with unknown structural behavior is divided into a finite number of simple geometric elements with known structural behavior, known as a mesh. At the boundaries of the elements, the displacements are aligned with the adjacent elements, and a matrix equation is formed. The equation is numerically solved, and the results are visible graphically and show the calculated stresses, deformations and displacements that occur in the model when forces are applied.

2.2.1. Choosing a Software Application

Due to the fact that the 3D virtual model was created in the 3D CAD application Creo Parametric, we carried out the simulations in Creo Simulate. Both Creo Parametric and Creo Simulate work on a single platform, and Creo Simulate is embedded as a module in the Creo Parametric environment. A great advantage is that if the analyses point to the fact that it will be necessary to change the geometry to achieve the desired mechanical properties, it is possible to switch to modeling mode, modify the geometry, and switch back to the simulated environment again in a short time, where repeated analyses will be performed.

Other best-known programs for creating simulations include Abaqus, Adina, ANSYS, Marc, Nastran, HyperWorks, Creo-Simulate, etc.

2.2.2. Virtual Stress-Strain Analyses

When designing new models, an important part is to anticipate their behavior in different situations. Therefore, it is necessary to perform many calculations so that the models and the resulting assemblies are appropriately dimensioned and thus ensure their strength and long service life. Before the calculations begin, the necessary unit values are inserted into the individual components of the assembly, without which the calculations cannot be performed. These include Density ρ, Young’s modulus E, and Poisson’s number μ (ν in some sources).

The values for individual quantities will come from the materials described in Section 2.1.2.

2.3. Prototype 3D Printing Phase

3D printing is an additive manufacturing process in which a three-dimensional object is produced by adding materials layer by layer, while many 3D printers also allow the use of several types of materials at the same time or multiple color variations of the same material to achieve the color of the printed product. The melting or deposition of materials as such, specifically in the areas defined by the cutting planes, prevents the waste of materials. In addition, the layered manufacturing process allows for the production of complex parts, such as lattice structures. The development of usable materials for 3D printers is very dynamic, and dozens of new materials are developed every year, which increases the potential of this technology for years to come. The sub-phases of the prototype 3D printing phase consist of:

• selection of 3D printers according to the selected materials;
• selection of 3D printers according to the dimensions of the prints;
• selection of 3D printers according to multi-color printing;
• export models to suitable printer formats;
• composition of the prototype.

2.3.1. Selection of 3D Printers According to the Selected Materials

All three materials selected in Section 2.1.2 are cartridges for additive printing using FDM technology. There are many 3D printers available on the market.

Table 1. 3D printers according to compatibility with selected materials.

3D Printer	Material
	ABS-M30	PC-ABS	ASA
Stratasys F120	*		*
Stratasys F170	*		*
Stratasys F270	*		*
Stratasys F370	*	*	*
Fortus 380mc	*	*	*
Fortus 380mc Carbon Fiber			*
Fortus 450mc	*	*	*
Stratasys F900	*	*	*
Makerbot Method X	*
Ultimaker S5	*
CraftBot FLOW IDEX XL	*

*—The 3D printer is capable of using a cartridge with the desired material.

shows the 3D printers according to their compatibility with the selected materials.

2.3.2. Selection of 3D Printers According to the Dimensions of the Prints

When choosing 3D printers, it is also necessary to consider their workspace and the maximum dimensions of the virtual models. From a strength point of view, it would be more advantageous for each part of the device to be printed in one piece. The lower part of the assembly will be the largest in size, and its diameter will be in the range of values 37–39 cm, with height in the range of 9–12 cm. Other parts will be smaller.

Table 2. Workspace and number of 3D printer extruders.

3D Printer	Workspace (cm)	Filament (pcs)	Support (pcs)
Stratasys F120	25.4 × 25.4 × 25.4	1	1
Stratasys F170	25.4 × 25.4 × 25.4	1	1
Stratasys F270	30.5 × 25.4 × 30.5	2	2
Stratasys F370	35.5 × 25.4 × 35.5	2	2
Fortus 380mc	35.5 × 30.5 × 30.5	1	1
Fortus 380mc Carbon Fiber	35.5 × 30.5 × 30.5	1	1
Fortus 450mc	40.6 × 35.5 × 40.6	2	2
Stratasys F900	91.44 × 60.96 × 91.44	2	2
Makerbot Method X	19.0 × 19.0 × 19.6	2	2
Ultimaker S5	33.0 × 24.0 × 30.0	1	1
CraftBot FLOW IDEX XL	42.5 × 25.0 × 50.0	1	1

shows 3D printers, their workspace for prints, and the number of extruders (print heads) for filaments and supports.

2.3.3. Selection of 3D Printers According to Multi-Color Printing

The 7 parts of the assembly come in different colors according to the customer’s requirements. In some cases, the part of the central decoration can also be two-colored. Therefore, it is necessary to consider the color range that is available for each type of material and 3D printer so that the following color shades can be considered in the design of the car steering wheel.

Table 3. Color shades available for compliant 3D printer materials.

3D Printer	Material
	ABS-M30	PC-ABS	ASA
Stratasys F120 Stratasys F170 Stratasys F270		-
Stratasys F370 Fortus 380mc Fortus 450mc Stratasys F900
Makerbot Method X
Ultimaker S5 CraftBot FLOW IDEX XL		-	-

lists 3D printers, compliant materials, and available color shades of cartridges.

2.3.4. Export Models to Suitable Printer Formats

In order for a 3D printer to be able to print a design from any 3D application, it needs a so-called digital plan of the building. It is data about digital design, such as geometry, textures, colors, and materials used. There are several file formats that can contain this data. From these files, known as 3D file formats, the 3D printer is then able to read the digital design of the object and print it accordingly. Some of the most well-known 3D file formats are STL, OBJ, AMF, and 3MF.

2.3.5. Composition of the Prototype

After all the parts have been printed, the steering wheel assembly will be completed. The assembly diagram of the composition is shown in Figure 2, with Bottom_part being considered as the starting part of the assembly.

2.4. Test Phase

The steering wheel consists of selected materials which have complied with the requirements of Section 2.1.2. These are polymeric materials that are additively applied in different layers to form the final product. Polymeric materials are highly variable in chemical and morphological composition, so it is not possible to determine uniform conditions for all materials under which tests are to be carried out, and the relevant standards usually regulate these conditions only in general terms. The choice of specific conditions for a particular test and material is usually entrusted to either material standards or the decision is left to the professional discretion of the surgeon. The aim of the test phase is to verify that the prototype of the interior equipment meets all the required mechanical properties. The subphases of the test phase are:

• compression test;
• hardness test.

2.4.1. Compression Test

The principle of the test is as follows: a test body with a cylindrical diameter, inserted between two bases, is subjected to a compressive force until it is crushed. During the test, the test cylinder deforms irregularly in height and acquires a characteristic barrel-shaped shape.

2.4.2. Hardness Test

Hardness is a mechanical property of a material expressed by resistance to surface deformation caused by the action of a geometrically determined, defined body. Hardness is not defined as a physical quantity, and its value depends on the complex surface properties of the material to be tested and on the test conditions under which the hardness is determined. The most commonly used tests are those, according to Brinell, Vickers, Rockwell, and Shore.

3. Virtual Analyses

Before starting work in Creo Simulate [30], we had to plan all aspects of the simulation model development in advance. We considered whether the methods and elements we used to create the models would allow us to reduce the mesh creation time and calculations of the required simulations so that the models could be easily optimized and what impact the optimization and reshaping would have on all related parts.

Work in Creo Simulate can be divided into several phases:

• meshing;
• creation of constraints and loads;
• material assignment;
• define analytics;
• results of analyses;
• optimization.

3.1. Meshing

Once the model is created, it is possible to generate a finite element mesh. It is possible to connect volumes, center surfaces, and shells separately or in any combination. The creation of the mesh can be automatic or controlled by settings. These settings verify that the program will be able to create a mesh or detect problematic geometry that caused the mesh creation failure.

Six models of the assembly were loaded into Creo Simulate. The Central_ornament model was excluded from the simulation model for two reasons: simplification, and we also did not expect it would significantly affect the analyses.

After setting the meshing conditions to the condition that the element size does not exceed 20 mm, a mesh with 17,096 tetragonal elements was generated.

3.2. Creation of Constraints and Loads

Constraints and loads define the real-world environment that the model will encounter. Creo Simulate enables simulations of model behavior under loads and constraints that are defined when performing standard analyses and sensitivity studies. The optimal shape and weight of the model may also depend on the loads you define. For structural analysis, a load is the force, momentum, compression, acceleration, velocity, or temperature that is applied to a part of the model or the entire model.

Two loads are required for steering wheel simulations. One is to ensure its fixation (limitation of movement, boundary conditions), and the other is to force action.

The model is fixed from the bottom through a circular hole through a screw connection to the steering rod. The simulation of this load was the removal of all degrees of freedom (fixation) to a given circular opening.

The force action on the assembly had to be considered from several points of view. We relied on crash test analyses and other sources on the subject [31,32,33]. We determined the initial compressive force load at 5000 N = 509,858 kg. This value should be sufficient for the safe operation of the prototype. We loaded the assembly with a compressive force in the direction perpendicular to the floor plan.

Figure 3 on the left shows the fixation on the circular hole, and on the right shows the compressive force acting on the steering wheel.

3.3. Material Assignment

A material assignment is necessary for the correct start of the simulation. For individual analyses of different materials, the process is similar and simple, as the mesh, all constraints and forces remain unchanged, and only the material changes. This greatly speeds up the simulation process for material variations. The visibility of the material assignment is displayed both in the simulation model tree and in the graphics area. ASA material was chosen as the first test material.

Table 4. Material characteristics of three suitable materials of 3D printers.

Material	Density ρ (kg/m3)	Young’s Modulus E (GPa)	Poisson Number μ (ν)
ABS-M30	1040	2.4	0.35
PC-ABS	1200	1.99	0.37
ASA	1070	2.14	0.32

shows the constant values for each item.

3.4. Defining Analyses

Analyses and design studies provide information about the strengths and weaknesses of the model under different conditions. When creating the analysis, we determine the loads and constraints on the model and how Creo Simulate should calculate the effects of loads and constraints on the model. Design studies use one or more analyses to study the effects of changes on the model (standard studies), to determine the sensitivity of your model to changes (sensitivity studies), or to determine which combination of parameters makes the model the best or the strongest (optimization studies).

We chose a structural static analysis. The program calculates stresses, deformations, and displacements based on the specified constraints and loads. These will express whether the model is deformed or broken, at what point it can break, and how its shape will change. The program counts on the condition of von Mises’ plasticity. Von Mises stress is generally considered to be the most accurate in predicting the failure of ductile matter.

3.5. Results of Analyses

Within the results, it is possible to display several windows and additionally set the desired views. When evaluating the results, it is important to rely on the contractual values of the yield strengths of all three tested materials, as exceeding them will cause partial or permanent failure of the assembly components at the defined load.

Table 5. Compression yield strength for test materials.

Material	Yield Strength Re Compression (MPa) (kg/m3)	Yield Strength Re Tensile (MPa)
ABS-M30	88.3	30.8
PC-ABS	96.5	36.5
ASA	75.4	32.8

shows the compression and tensile yield strengths for the materials to be tested.

At a load of 5000 N, the stress analysis results proved to be too high and exceeded the yield strength of compression. The highest stress values were achieved on the Bottom_part, so we proceeded to optimize it. We have increased the thickness of the material on the arms, and we have implemented several edge roundings that prevent the concentration of stresses. The change from the original shape is visible in Figure 4.

Subsequently, it was necessary to change the other 4 parts of the set: upper right, upper left, lower right, and lower left. The Top_part and the Central_ornament remained unchanged.

After optimizing the entire assembly, we proceeded to the simulation again. Given that the Bottom_part is the most heavily loaded part, we continued the optimization only with it. We have simplified the model. We updated the mesh before the simulation, and 8089 elements were created. The mesh is shown in Figure 5.

After adjusting the mesh, setting the compressive force of 5000 N, and assigning the ASA material, we started the simulation. Figure 6 shows the stresses, and Figure 7 shows the displacements of the model Bottom_part in a deformed state in the side view.

Subsequently, ABS-M30 and PC-ABS materials were also tested.

Table 6. Values of stresses and displacements for the tested materials.

Material	Maximum Stress (MPa)	Maximum Displacement (mm)	Yield Strength Re Compression (MPa) (kg/m3)
ABS-M30	39.01	16.72	88.3
PC-ABS	40.05	20.27	96.5
ASA	38.89	18.62	75.4

shows the values for stresses and displacements for all three tested materials and, for comparison, also the yield strength [34] for compression.

For a given load of 5000 N, all three tested materials met the design requirements, while the differences in stresses and displacements were minimal.

Table 7. Weights of individual parts of the assembly for the tested materials.

	ABS-M30	PC-ABS	ASA
Bottom_part	2120 g	2446 g	2181 g
Top_part	183 g	211 g	188 g
Central_ornament—cross Stredová_ozdoba_kriz	3.8 g	4.4 g	3.9 g
Left_upper_ornament	7.7 g	8 g	7.9 g
Right_upper_ornament	10.3 g	11.2 g	10.5 g
Left_lower_ornament	13.2 g	15.3 g	13.6 g
Right_lower_ornament	13.1 g	15 g	13.5 g

shows the weights of the individual parts of the steering wheel assembly for each material. This data is used to order print cartridges for the 3D printer.

3.6. Optimization of the Bottom_Part Model

Another question was whether the optimization of the shape of the Bottom_part component would have a significant impact on the strength of the model, the stresses, and the displacements achieved. The second aspect was also material savings, which would lead to a reduction in the price of the prototype. For optimization, we chose to hollow a circular cross-section in the handle. The cross-section of the handle part is shown in Figure 8. We tested two diameters: 20 and 25 mm.

Table 8. Values of masses, stresses, and displacements for the tested materials of the optimized Bottom_part model.

		ABS-M30	PC-ABS	ASA
Bottom_part original without hole	Weight (g)	2120	2446	2181
	Stress (MPa)	39.0	40.05	38.89
	Displacements (mm)	16.72	20.27	18.62
Bottom_part Optimized φ20 mm	Weight (g)	1660	1915	1708
	Stress (MPa)	49.04	48.92	49.12
	Displacements (mm)	20.63	24.99	22.97
Bottom_part Optimized φ25 mm	Weight (g)	1558	1798	1603
	Stress (MPa)	60.12	60.15	58.33
	Displacements (mm)	23.37	28.30	26.04

shows the values for weights, achieved stresses, and displacements for the original shape, as well as two optimized shapes for the Bottom_part model.

Table 8 shows that both optimized parts met the design requirements for all three tested materials, with minimal differences in stresses and displacements. Due to the φ20 mm hole in the handle, the weight of the model has decreased: ABS-M30 by 460 g, PC-ABS by 530 g, and ASA by 470 g. Due to the φ25 mm hole in the handle, the weight of the model has decreased: ABS-M30 by 560 g, PC-ABS by 648 g, and ASA by 578 g. A decrease in the weight of the model will significantly contribute to reducing the price per prototype.

4. 3D Printing and Prototype Completion

After the virtual simulations were completed, the selection of a suitable 3D printer, printing material and the final completion of the prototype followed. The only limiting factor for the 3D printer chosen was the size of the Bottom_part. It was necessary to choose a 3D printer whose workspace allowed it to print 38.7 cm in two directions. Table 2 shows that the following 3D printers met this criterion: Fortus 450mc (Fortus, Leeds, UK), Stratasys F900 (Stratasys, Eden Prairie, MN, USA), and CraftBot FLOW IDEX XL (CraftBot, Budapest, Hungary). However, after consulting with an employee of a company specializing in professional 3D printing of prototypes, it turned out that only the Stratasys F900 printer was suitable, as in the Fortus 450mc and CraftBot FLOW IDEX XL printers, the part would need to be rotated 90 degrees, which would significantly increase the consumption of support material and the total price of the prototype. (Note. Within the Slovak Republic, we have not found a commercial company specializing in professional 3D printing that owns a 3D printer with the required printing area. That is why we approached a company in the Czech Republic).

The choice of printing material was influenced by Table 3. ASA was chosen as the material, as it has the most numerous color variability.

We exported the report files to STL format and sent them for 3D printing. Subsequently, after loading the files into the 3D printer, the Czech company prepared a price offer for the prototype. This price exceeded our expectations and budget several times. For this reason, we refused to print the prototype in the Czech company and proceeded to an alternative solution. We sent the prototype to a Slovak company, which printed it on a printer using FDM printing from PET-G material for visualization. The price for the prototype was 1/6 of the original price. The completed color prototype is shown in Figure 9.

5. Mechanical Tests

To verify the required mechanical properties, samples from compliant materials were printed by the Czech company. Since these are polymeric materials and an additive manufacturing method, the properties change depending on which layer of material is applied. The samples were printed on a Stratasys Fortus 450mc 3D printer; the thickness of the printed layer was 0.25 mm (other available layer thicknesses are 0.127 mm, 0.178 mm, and 0.330 mm) and were subjected to compression and hardness testing.

5.1. Compression Test

For this test, samples of a cylindrical shape, with a diameter of 15 mm and a height of 15 mm, were prepared and are shown in Figure 10. Five samples were prepared for each material.

Records of the loading forces (X-axis) for individual samples and materials are shown in Figure 11.

The diagrams showed that these are relatively tough materials. After subtracting the force loads and calculating the loaded area, the yield strengths for the individual samples were calculated. The average values of the compression yield strength for each material are shown by the numerical value above the red column in Figure 12.

Table 6 lists the yield strengths for the materials declared by the manufacturer. When compared with the measured yield strengths, it turned out that the values differed considerably. Most likely, the higher thickness of the applied layer is the cause. Nevertheless, they meet the requirements that were placed on the construction and load of the steering wheel, with ABS-M30 appearing to be the most suitable material in terms of compression.

5.2. Hardness Test

For this test, cuboid-shaped samples with dimensions of 30 mm × 30 mm × 20 mm were prepared (Figure 13). 1 sample was prepared for each material. The initial intention was to measure hardness according to Rockwell, as the manufacturer also states the hardness of the materials according to this method. However, the measurement using this method was not successful.

We chose another available method—Shore hardness measurement. This method is based on pressing the hardness tester identifier into the material and is used for plastic materials. Individual measurements are located at a distance of at least 12 mm from the edge and 5 mm from each other. Two types of identors are used, while for hard materials (hardness in the range of 60–100), identor D is used. Ten measurements were taken on each sample. The average hardness values for each material are shown by the numerical value above the red column in Figure 14.

In terms of hardness, ABS-M30 takes on the highest values, while the other two differ minimally in hardness.

The tests raised the question of whether the materials used for 3D printing are competitive against the same materials used in plastic injection molding. Thanks to a company from Žilina, engaged in the production of plastic products by injection molding of thermoplastics, we obtained samples of two injection molded materials: PC-ABS and ASA (Figure 15). These samples are used to compare the hardness of injection molded and printed materials with identical markings.

Ten measurements were taken on each sample. The average hardness values for each material are shown by the numerical value above the red bar in Figure 16.

In terms of hardness, the PC-ABS material acquires higher values, with ASA differing only minimally.

When comparing the hardness of samples printed on a 3D printer and samples made using injection molding, it turned out that they have a comparable hardness, and therefore, products made using 3D printing from PC-ABS and ASA materials are competitive in terms of hardness to products made using plastic injection molding technology.

6. Conclusions

3D printing technologies have become invaluable in rapidly bringing products to market, reducing production costs, and allowing customers to influence the final design of products. These technologies enable the replacement of expensive machine parts with printed components that meet required mechanical properties while being significantly more cost-effective to produce. Moreover, there is now a wide range of free software available, allowing even average users to create virtual 3D models and print them, either using their own 3D printers or through companies offering professional 3D printing services. Additionally, 3D printer manufacturers collaborate closely with CAD application developers to ensure seamless compatibility between CAD output files and 3D printers. With the ability to print even moving components, the advancement of 3D printing technology continues to accelerate at a remarkable pace.

The production of plastic products has traditionally relied on injection molding, where hot plastic is injected into molds. However, in recent years, 3D additive printing has become a viable alternative for manufacturing plastic components. A key question that arises is whether products made through 3D printing exhibit the same or at least adequate mechanical properties compared to those produced by injection molding. Due to the wide range of materials available for 3D printing, it is essential to continually test the mechanical properties of new products intended for commercial use and compliance with standards.

The article presents the use of 3D virtual simulations, 3D printing, and deformation tests for the design of a new prototype of a car steering wheel. The methodology is divided into four phases: preparatory phase, virtual simulation phase, 3D prototype printing phase, and testing phase. This article explores the application of 3D virtual simulations, 3D printing, and deformation testing in designing a new prototype of a car steering wheel. The methodology consists of four phases: the preparatory phase, the virtual simulation phase, the 3D prototype printing phase, and the testing phase.

The preparatory phase involved gathering source data for the virtual 3D model of the steering wheel and defining material characteristics. The selected materials needed to meet the criteria for strength, abrasion resistance, UV stability, and resistance to extreme temperatures. Three materials met these requirements: ASA, ABS-M30, and PC-ABS.

The virtual simulation phase required advanced theoretical knowledge of virtual simulations. Initial strength simulations using the three tested materials showed that the steering wheel model could not withstand the test load of 5000 N. Consequently, the design had to be optimized. After optimization and re-simulation, the model successfully withstood the required 5000 N load.

The 3D printing phase required an in-depth understanding of professional 3D printers available in Slovakia. The selection criteria included compatibility with the required materials, adequate work surface size, and multi-color printing capabilities. A key constraint was the size of the bottom part, which measured 38.7 cm in two dimensions. Three printers met the initial requirements: Fortus 450mc, Stratasys F900, and CraftBot FLOW IDEX XL. However, after careful consideration, the Stratasys F900 was selected, as using the other two printers would require rotating the bottom part by 90 degrees, significantly increasing support material usage and overall costs. For financial reasons, the prototype was printed for demonstration purposes using PET-G material (Figure 9).

The testing phase involved deformation tests on samples printed from the selected materials. Two standardized 3D models were created: a cylindrical sample for compression testing and a cuboid-shaped sample for hardness testing. For the compression test, five samples of each material (ASA, ABS-M30, and PC-ABS) were printed using a Fortus 450mc printer with a layer thickness of 0.25 mm. Comparing the manufacturer-provided compression yield strength values (Figure 6) with measured values (Figure 12) revealed significant differences, likely due to the thicker printed layers. However, all samples met the required strength specifications for the steering wheel design, with ABS-M30 proving the most suitable in terms of compression performance. For the hardness test, each material was tested for hardness ten times. The initial plan was to use the Rockwell hardness method, as it is the standard cited by the manufacturers. However, this method proved unsuccessful, so Shore hardness was used instead. Among the tested materials, ABS-M30 showed the highest hardness values, while ASA and PC-ABS displayed minimal differences in hardness (Figure 14).

The study also examined whether 3D-printed materials are competitive with the same materials produced via plastic injection molding. Samples of injection-molded PC-ABS and ASA were obtained. Results showed that injection-molded PC-ABS had slightly higher hardness values, while ASA exhibited minimal differences (Figure 16). Comparisons revealed that the hardness of 3D-printed and injection-molded samples is comparable, confirming the competitiveness of 3D-printed PC-ABS and ASA in terms of hardness.

These findings address the research objectives and provide a comprehensive evaluation of the issue. In conclusion, the developed methodology and procedures can be effectively applied to similar cases, such as the creation of a 3D-printed prototype for a car steering wheel.