Computational Design and Additive Manufacturing of 3D-Printed Prosthetics for Enhanced Mobility and Performance

Abstract

This paper discusses the potential application of computational design and additive manufacturing in veterinary prosthetics, demonstrated with the example of a feline limb. A finite element analysis (FEA)-based design optimization framework was used to develop eight prosthetic leg geometries in CAD and analyze them in ANSYS (2024R) under a static loading condition, to evaluate their performance under the loading condition. Structural variations were in the form of grooves, holes and shell reinforcements, which were investigated to see how they affect stiffness, stress distribution and viability of the 3D-printed prosthetics. Design variations were introduced through the inclusion or exclusion of structural attributes such as grooves, holes, and shell reinforcements. The simulations evaluated total deformation, von Mises stress, and equivalent elastic strain to determine the mechanical efficiency of each configuration. Results showed that designs incorporating shells and holes provided the best overall performance, as groove-free designs minimized stress concentrations and achieved the highest stiffness. Notably, the configuration featuring a hole and shell without grooves achieved the lowest mean deformation (14.09 µm) and stress values, making it the most structurally viable and suitable for real-life application. This study highlights the potential of 3D printing to produce cost-effective, patient-specific prosthetics and underscores the importance of structural optimization for improving biomechanical compatibility and mobility. The next stage of this work will involve fabricating the optimized design using 3D printing, followed by mechanical testing to validate the simulation results and assess real-world performance. Future work will also incorporate topology optimization to further reduce weight while maintaining structural integrity.

1. Introduction

Computational design and additive manufacturing have converged in meaningful ways to transform prosthetic device development for both humans and animals. In veterinary medicine, prosthetics present a promising alternative to conventional approaches—such as euthanasia or amputation—when treating limb deformities or injuries. Studies by Mich [1] and Carr et al. [2] have shown that animal prostheses can improve mobility, prevent joint degeneration, and enhance overall quality of life. However, complications such as skin irritation and device failure remain challenges. Outcomes are also strongly influenced by factors such as the degree of disarticulation and the prosthetic type [3]. The increasing accessibility of 3D printing has further expanded the possibilities for veterinary prosthetics [4]. This technology offers functional and effective interventions, as evidenced by retrospective reviews in clinical practice. One of its most notable advantages is the ability to significantly reduce both production costs and lead times compared to traditional manufacturing methods [5]. Custom implants and prosthetics—once costly and labor-intensive—can now be fabricated quickly and affordably [6,7], enabling veterinarians to provide tailored solutions that were previously unattainable. As printing resolution and material capabilities advance, the durability and performance of animal prosthetics have improved, with materials such as titanium and biocompatible polymers producing lighter, stronger devices [8]. Beyond prosthetics, 3D-printed models aid veterinarians in visualizing complex anatomy for surgical planning, while printed scaffolds support bone regeneration in severe fractures or defects, accelerating recovery and reducing complications [9].

Despite these advantages, several limitations persist. Selecting materials that balance durability and biocompatibility remains a challenge, particularly with emerging options such as resorbable polymers and metal alloys [10]. While some materials exhibit excellent mechanical performance, their long-term effects—such as degradation, immune responses, or infection risk—are not fully understood [8,11]. Regulatory uncertainty, the need for extensive safety evaluations, and ethical considerations regarding animal welfare further complicate clinical adoption. Advancements in surgical techniques and design tools, including osseointegration and computer-aided design, have broadened the scope of veterinary prosthetic applications [12]. While canine prosthetics have achieved notable success, issues such as skin problems and patient non-compliance highlight the need for continued refinement [13,14]. Applications extend beyond domestic animals; for example, prosthetic solutions have been developed for deer [15], illustrating the importance of biomechanical compatibility and cross-disciplinary collaboration [12,14]. Material choice is also pivotal. ABS, an expensive yet versatile polymer, has become a key focus in 3D printing [16]. Research shows that PC-ABS blends have superior elastic limits and load-bearing capacity compared to pure ABS or PC [17]. Carbon nanotube reinforcement further enhances ABS strength and stiffness, surpassing even the highest-grade ABS [18]. Additionally, recycled ABS (rABS) demonstrates mechanical properties comparable to virgin ABS, with only slight reductions in impact resistance and tensile strength [19]. Print parameters, such as layer height, also significantly affect performance, with lower heights (0.1 mm) outperforming higher ones (0.2 mm) [11]. These findings highlight both the technical potential and sustainability of ABS-based prosthetics.

The integration of advanced computational tools has further revolutionized prosthetic design. Innovations such as biomimetic structures, AI-driven optimization, and finite element analysis (FEA) have led to lighter, more resilient, and more adaptable devices [20,21]. FEA, in particular, enables precise simulation of mechanical stress, strain, and user comfort, thereby reducing reliance on trial-and-error in prototype testing [22]. Its application extends from studying socket–residuum interactions to analyzing athletic performance in prosthetic limbs [23,24,25,26]. This computational approach helps bridge the performance gap between traditional and 3D-printed devices by improving design verification, material selection, and production efficiency. Biorobotics and biomechanical research also play critical roles in advancing prosthetic function. Examples such as the prosthetic sea turtle flipper designed by van der Geest and Garc [27] showcase how robotics can validate designs without direct animal testing. Similarly, human lower-limb robotic prosthetics, which replicate joint dynamics and natural motion, demonstrate how knowledge exchange between animal biomechanics and human prosthetic development drives innovation [28]. In some cases, animal-focused technologies have even surpassed comparable human devices [29,30,31,32].

Building on these developments, the present study investigates the potential of computational design and additive manufacturing in creating optimized, 3D-printed prosthetic limbs for feline patients. Eight prosthetic leg geometries are modeled and analyzed using FEA to evaluate how structural features—such as grooves, holes, and internal shells—affect mechanical performance under static loading. The objective is to identify the most mechanically efficient configuration that minimizes stress, strain, and deformation, thereby contributing to the creation of cost-effective, patient-specific prosthetics with improved biomechanical compatibility and functionality.

2. Materials and Methods

Eight unique prosthetic leg models were developed using Computer-Aided Design (CAD) software (2024R). Each model was created by systematically varying three key structural features to investigate their influence on mechanical performance.

The key design variables were:

• Internal Structure: This variable defines the internal composition of the prosthetic’s main body. Two configurations were tested:

• Solid Core: A design with a completely solid interior, providing maximum material density.
• Holed Core: A design where cylindrical voids (holes) were strategically patterned through the interior of the main body to reduce weight and material usage.

2.

External Shell: This variable refers to the addition of a thin, uniform outer layer, or “shell,” that encases the main body of the prosthetic. The configurations were:

• With Shell: A design that includes a continuous external shell of a specified thickness (e.g., 2 mm) that is fully integrated with the core structure.
• No Shell: A design where this external shell is omitted entirely.

3.

Surface Topography: This variable relates to the texture of the prosthetic’s exterior surface. The two configurations were:

• With Grooves: A design featuring recessed channels (grooves) machined into the external surface.
• No Grooves: A design with a smooth, uniform external surface, where the grooves are omitted.

By combining these variables, a total of eight distinct design configurations (2 internal structures × 2 shell options × 2 surface options = 8 models) were generated for analysis (Figure 1 and Figure 2). All the designs of the prosthetics were intended to be constructed using ABS (Acrylonitrile Butadiene Styrene) material. ABS was selected because of its desirable mechanical properties and also due to its suitability for 3D printing. While ABS is not a biocompatible material, it has been used effectively for external veterinary prosthetics where direct contact with tissue is not required, due to its strength, durability, and ease of printing. However, for future applications using filament-based 3D printing that may demand higher biocompatibility, materials such as Nylon (PA12 or PA6) could offer a suitable alternative. These materials are known for their excellent mechanical properties, including high tensile strength, impact resistance, and low weight, making them well-suited for external prosthetics, braces, and structural connectors. A discussion on this alternative has been added to the revised manuscript.

The standard parameters of the ABS material, Young’s modulus (2.3 GPa) and Poisson ratio (0.35) were keyed into ANSYS. ANSYS was used to mesh each design and this was performed using a constant mesh size of 2 mm (Figure 3). The size of this model was chosen to ensure that the calculations and results mesh independently when it comes to local stresses and strains. The No-hole, No-shell (Groove) model was run through a mesh convergence study. The size of elements varied between 1 and 10 mm and the maximum deformation reduced with a monotonic trend between 121.84 µm (1 mm) and 114.17 µm (10 mm). With a 2 mm (120.63 µm) baseline, the relative variation is +1.0% at 1 mm and 5.36% at 10 mm. The sequential error between adjacent meshes is no more than 1.76% on average and less than 1% with meshes 5 mm and larger, with 0.30% at 10 mm. These trends show that the response is becoming independent of the mesh; a mesh of ~3 mm is a reasonable trade-off between accuracy and cost. This is clearly illustrated in

Table 1. Mesh Convergence Study—No-Hole, No-Shell (Groove) Configuration.

Mesh Size (mm)	Maximum Deformation (µm)	% Change from 2 mm Mesh	% Error (vs. Previous)
1	121.84	0.98	0
1.5	121.31	0.56	0.41
2	120.63	0	0.56
3	118.54	−1.71	1.74
4	116.49	−3.41	1.76
5	115.67	−4.09	0.71
7	114.51	−5.05	1.01
10	114.17	−5.36	0.30

.

On the models, at the top, a stationary support was placed to represent the point where the limb of the cat would be attached. When the robot was mounted, the arm looked like a real prosthetic leg by getting rid of these motions. On the bottom of each prosthetic, a vertical force of 11.5 N was applied to represent the weight of one leg when a human stands still. The studies show that a healthy domestic cat is usually between 3.6 and 5.4 kg (8–12 pounds) in weight [23]. The average weight of a domestic cat is 4.6 kg, so assuming that this weight is distributed equally among four legs, you would obtain a value of 11.3 or 11.5 N. This state renders the test more realistic to the kind of stresses that the body is subjected to during normal movement or at rest. The simulation was set up to determine the performance of each design in terms of the following main output parameters as standards:

Total Deformation—to measure the total change in the material due to stress.

$$\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l} \mathrm{D}\mathrm{e}\mathrm{f}\mathrm{o}\mathrm{r}\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}=\sqrt{{{\mathrm{U}}_{\mathrm{x}}}^2+{{\mathrm{U}}_{\mathrm{y}}}^2+{{\mathrm{U}}_{\mathrm{z}}}^2},$$

(1)

where U_x, U_y, and U_z are displacements in X, Y, and Z directions.

Von Mises Stress—to inspect stress patterns and to detect the chance of material failure.

$${\mathsf{\epsilon }}_{\mathrm{e}\mathrm{q}}=\sqrt{\left[\left({\displaystyle \frac{1}{2}}\right)\times ({({\mathsf{\epsilon }}^1-{\mathsf{\epsilon }}^2)}^2+{({\mathsf{\epsilon }}^2-{\mathsf{\epsilon }}^3)}^2+{({\mathsf{\epsilon }}^3-{\mathsf{\epsilon }}^1)}^2)\right]}$$

(2)

where ${\mathsf{\epsilon }}^1, {\mathsf{\epsilon }}^2, {\mathsf{\epsilon }}^3$ are the principal strains in 3D.

Equivalent Elastic Strain–to find out the elastic behavior of the material, use Equivalent Elastic Strain.

$${\mathsf{\sigma }}_{\mathrm{e}\mathrm{q}}=\sqrt{\left[{\displaystyle \frac{({({\mathsf{\sigma }}^1-{\mathsf{\sigma }}^2)}^2+{({\mathsf{\sigma }}^2-{\mathsf{\sigma }}^3)}^2+{({\mathsf{\sigma }}^3-{\mathsf{\sigma }}^1)}^2)}{2}}\right]}$$

(3)

where σ¹, σ², σ³ = principal stresses.

All the simulations results were analyzed to determine the hole, shell and groove configurations gave the maximum strength, a stable structure and little variations in shape. Due to this analysis, informed decisions could be made regarding the most appropriate design of prosthesis among cats. To evaluate the relative performance of each design compared to the reference design, percentage changes were calculated using the following formulas:

$$\mathsf{\Delta }\mathrm{D}\mathrm{e}\mathrm{f}\mathrm{o}\mathrm{r}\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\left(\%\right)=\left({\displaystyle \frac{\left(\mathrm{D}\mathrm{e}\mathrm{s}\mathrm{i}\mathrm{g}\mathrm{n} \mathrm{D}\mathrm{e}\mathrm{f}\mathrm{o}\mathrm{r}\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}-\mathrm{R}\mathrm{e}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{D}\mathrm{e}\mathrm{f}\mathrm{o}\mathrm{r}\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\right)}{\mathrm{R}\mathrm{e}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{D}\mathrm{e}\mathrm{f}\mathrm{o}\mathrm{r}\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}}\right)\times 100$$

(4)

$$\mathsf{\Delta }\mathrm{S}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{i}\mathrm{n}\left(\%\right)=\left({\displaystyle \frac{\left(\mathrm{D}\mathrm{e}\mathrm{s}\mathrm{i}\mathrm{g}\mathrm{n} \mathrm{S}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{i}\mathrm{n}-\mathrm{R}\mathrm{e}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{S}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{i}\mathrm{n}\right)}{\mathrm{R}\mathrm{e}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{S}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{i}\mathrm{n}}}\right)\times 100$$

(5)

$$\mathsf{\Delta }\mathrm{S}\mathrm{t}\mathrm{r}\mathrm{e}\mathrm{s}\mathrm{s}\left(\%\right)=\left({\displaystyle \frac{\left(\mathrm{D}\mathrm{e}\mathrm{s}\mathrm{i}\mathrm{g}\mathrm{n} \mathrm{S}\mathrm{t}\mathrm{r}\mathrm{e}\mathrm{s}\mathrm{s}-\mathrm{R}\mathrm{e}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{S}\mathrm{t}\mathrm{r}\mathrm{e}\mathrm{s}\mathrm{s}\right)}{\mathrm{R}\mathrm{e}\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{S}\mathrm{t}\mathrm{r}\mathrm{e}\mathrm{s}\mathrm{s}}}\right)\times 100$$

(6)

$$\% \mathrm{C}\mathrm{h}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e} \mathrm{f}\mathrm{r}\mathrm{o}\mathrm{m} 2 \mathrm{m}\mathrm{m} \mathrm{M}\mathrm{e}\mathrm{s}\mathrm{h}=\left(\right(\mathrm{V}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e}\_\mathrm{i}-\mathrm{V}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e}\_2 \mathrm{m}\mathrm{m})/\mathrm{V}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e}\_2 \mathrm{m}\mathrm{m})\times 100$$

(7)

$$\mathrm{E}\mathrm{r}\mathrm{r}\mathrm{o}\mathrm{r} (\%)=|\mathrm{V}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e}\_\mathrm{i}-\mathrm{V}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e}\_\{\mathrm{i}-1\left\}\right|/\mathrm{V}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e}\_\mathrm{i}\times 100$$

(8)

$$\mathrm{I}\mathrm{m}\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{v}\mathrm{e}\mathrm{m}\mathrm{e}\mathrm{n}\mathrm{t} (\%)=(\mathrm{W}\mathrm{o}\mathrm{r}\mathrm{s}\mathrm{t}-\mathrm{B}\mathrm{e}\mathrm{s}\mathrm{t})/\mathrm{W}\mathrm{o}\mathrm{r}\mathrm{s}\mathrm{t}\times 100$$

(9)

These formulas were applied to compute the relative percentage deviation in deformation, strain, and stress for each design variant. The reference design selected was “Design 7: With hole with shell,” against which all other configurations were compared.

Mesh details for all eight 3D-printed materials are shown below.

For physical demonstration, 3D models corresponding to the four main categories (groove/no-groove × shell/no-shell) were printed, as illustrated in Figure 4. The following design configurations were analyzed and assigned as:

• Design 1: No Hole, No Shell (Groove)—Element Size 18,883
• Design 2: With Hole, With Shell (Groove)—Element Size 20,992
• Design 3: With Hole, No Shell (Groove)—Element Size 20,140
• Design 4: No Hole, With Shell (Groove)—Element Size 18,883
• Design 5: No Hole, No Shell (No Groove)—Element Size 19,581
• Design 6: With Hole, With Shell (No Groove)—Element Size 21,758
• Design 7: With Hole, No Shell (No Groove)—Element Size 21,730
• Design 8: No Hole, With Shell (No Groove)—Element Size 1958

3. Results and Discussion

Our mechanical simulations across the eight configurations reveal how the presence of grooves and the addition of a shell shape the structural performance. As shown in Figure 5, the configuration with a groove but without a hole or shell exhibited the highest deformation at 120.63 µm, indicating reduced stiffness and greater susceptibility to bending under load. Adding a shell to this same design reduced deformation to 99.105 µm, demonstrating the reinforcing effect of the shell in distributing stress more evenly and enhancing stiffness. However, the strongest performance was observed in the designs without grooves, regardless of whether a shell was included, with the lowest deformation measured at 64.775 µm. This highlights the critical role of grooves in weakening structural integrity, as their presence significantly diminishes the benefit provided by the shell. In contrast, removing grooves markedly increases stiffness even without a shell. Taken together, these findings suggest that eliminating grooves is more important for minimizing deformation and improving stability than simply adding a shell, though combining both strategies—groove removal and shell addition—offers the most robust structural solution.

The incorporation of holes into the structural designs produced clear changes in mechanical behavior, as shown in Figure 6. The configuration that combined a hole, a groove, and a shell exhibited the greatest deformation at 120.56 µm, revealing a substantial vulnerability when grooves and holes coexist, even in the presence of a reinforcing shell. This indicates that the weakening effects of these two features are likely additive, or even synergistic, in compromising stiffness. By contrast, designs that included a hole but omitted the groove—whether or not a shell was present—performed much better, with the lowest deformation values of 64.805 µm and 64.808 µm, reflecting a significant improvement in stiffness. This consistency across both shelled and unshelled versions underscores that grooves have a more detrimental effect than the potential benefits offered by shells. Similarly, the configuration with both a hole and groove but no shell showed slightly higher deformation at 68.505 µm, further confirming that grooves, rather than the absence of a shell, are the dominant factor driving mechanical weakness. Overall, these results make it clear that eliminating grooves is the most effective strategy for improving stiffness in structures with holes, while shells provide only minor mitigation. This finding is particularly relevant for applications that demand high strength and dimensional stability under load-bearing conditions.

We then turned our attention to elastic strain, which measures how much the material stretches when subjected to stress. Figure 7 presents the elastic strain values for all designs without holes, allowing us to isolate the effects of grooves and shells on structural performance. Among these configurations, the design that included a groove but lacked both a hole and a shell exhibited the highest elastic strain, reaching 0.00027954 µm/µm. This elevated strain suggests significant deformation under load, likely due to the groove creating a localized stress concentration that compromises material stiffness. In contrast, the designs without holes and without grooves—regardless of whether they included a shell—displayed the lowest elastic strain values, with a maximum of just 0.00016659 µm/µm. These results clearly demonstrate that the elimination of the groove significantly enhances the material’s ability to resist deformation, and that the presence of a groove has a much greater impact on strain behavior than the presence or absence of a shell. The design that included both a shell and a groove (but no hole) showed a moderately high strain value of 0.00021842 µm/µm, indicating that while the shell offers some reinforcement, it is insufficient to fully counteract the detrimental effects introduced by the groove. Overall, the data underscore the critical role of grooves in driving up elastic strain. While shells can provide a modest improvement in structural resilience, their impact is secondary when compared to the substantial strain-reducing benefits achieved by eliminating grooves. For applications where minimizing elastic deformation is essential, avoiding groove features in the design should be prioritized, with shells used as a secondary measure of structural reinforcement.

Figure 8 presents the elastic strain results for the models containing holes, highlighting how the presence or absence of grooves and shells influences material deformation under load. Among the tested configurations, the design featuring a hole, a groove, and a shell exhibited the highest elastic strain value at 0.00027703 µm/µm. This elevated strain indicates a pronounced stress concentration resulting from the combination of a hole and a groove, even when reinforced with a shell. The interaction between these two features appears to significantly weaken the structure’s ability to resist stretching. However, the design that included a hole and a shell but no groove showed a much lower elastic strain of 0.00014697 µm/µm, clearly demonstrating that removing the groove substantially reduces deformation, even when the hole remains. Similarly, the model with a hole and a groove but without a shell recorded a strain of 0.00017014 µm/µm—lower than the fully grooved and shelled design, but still considerably higher than any of the configurations that excluded grooves altogether. Interestingly, the design with a hole, no shell, and no groove produced the second-lowest elastic strain at 0.00014728 µm/µm, nearly identical to the strain observed in the shelled counterpart without a groove. This further reinforces the conclusion that groove removal has a more significant impact on reducing strain than shell addition. While shells do contribute to improving structural stiffness, their effectiveness is clearly secondary when compared to the benefits of eliminating grooves.

Finally, our analysis shifts to Von Mises stress, a critical metric used to evaluate how internal stresses are distributed within a structure and to identify potential failure points. Figure 9 and Figure 10 present the Von Mises stress results for the four design configurations without holes, emphasizing the influence of grooves and shells on stress concentration. Among these designs, the configuration that included a groove but lacked a shell exhibited the highest stress concentration, with a peak value of 0.58376 MPa. This clearly indicates that grooves act as stress concentrators, introducing structural vulnerabilities that can compromise the integrity of the part. Even when a shell was added to this grooved design, the maximum stress only dropped slightly to 0.45291 MPa, suggesting that while the shell offers some structural reinforcement, it is not sufficient to offset the negative effects introduced by the groove. However, the two configurations without grooves—regardless of whether a shell was present—both exhibited significantly lower stress values, topping out at 0.34451 MPa. This consistency across shell and non-shell versions strongly supports the conclusion that removing the groove is the most effective approach for minimizing Von Mises stress. The addition of a shell, while slightly beneficial, provides only a modest reduction in stress compared to the improvement gained from eliminating the groove entirely. These findings confirm that groove geometry plays a dominant role in determining stress concentration levels in structures without holes. Although shell inclusion contributes to enhanced stress distribution, its effectiveness is secondary to the impact of groove removal. For optimal structural integrity, particularly in designs where fatigue and high stress are concerns, eliminating grooves should be prioritized, with shells serving as supplemental reinforcements.

Table 2. Total Deformation, Equivalent Elastic Strain and Von Mises Stress of various designs.

Design Configuration	Total Deformation (µm)			Equivalent Elastic Strain (µm/µm)			Equivalent Stress (MPa)
	Min	Max	Avg	Min	Max	Avg	Min	Max	Avg
With Groove
No Hole, No Shell	0	120.63	25.127	1.18 × 10−10	2.79 × 10−4	2.9 × 10−5	2.4 × 10−7	0.586	5.67 × 10−2
With Hole, With Shell	0	120.56	22.46	7.55 × 10−10	2.77 × 10−4	2.62 × 10−5	5.99 × 10−8	0.573	5.12 × 10−2
With hole, no shell	0	68.505	11.95	9.07 × 10−10	1.7 × 10−4	1.59 × 10−5	1.45 × 10−7	0.355	3.08 × 10−2
No Hole, With Shell	0	99.105	18.84	1.01 × 10−10	2.18 × 10−4	2.43 × 10−5	2.03 × 10−7	0.453	4.73 × 10−2
Without Groove
No Hole, No Shell	0	64.78	15.63	2.98 × 10−11	1.67 × 10−4	1.87 × 10−5	5.93 × 10−8	0.344	3.76 × 10−2
With Hole, With Shell	0	64.805	14.01	1.24 × 10−11	1.47 × 10−4	1.72 × 10−5	8.76 × 10−9	0.299	3.45 × 10−2
With hole, no shell	0	64.808	14.09	2.24 × 10−12	1.43 × 10−4	1.74 × 10−5	2.34 × 10−9	0.296	3.49 × 10−2
No Hole, With Shell	0	66.77	15.634	2.98 × 10−11	1.67 × 10−4	1.87 × 10−5	5.94 × 10−8	0.345	3.75 × 10−2

and

Table 3. Prosthetic Design Performance Comparison with respect to Design 7.

Design Configuration	Avg Deformation (µm)	Avg Strain (µm/µm)	Avg Stress (MPa)	Δ Deformation (%)	Δ Strain (%)	Δ Stress (%)
No Hole, No Shell (Groove)	25.127	2.90 × 10−5	5.67 × 10−2	78.33	66.67	62.86
With Hole, With Shell (Groove)	22.46	2.62 × 10−5	5.12 × 10−2	59.4	50.57	45.71
With hole, no shell (Groove)	11.95	1.59 × 10−5	3.08 × 10−2	−15.19	−8.62	−11.43
No Hole, With Shell (Groove)	18.84	2.43 × 10−5	4.73 × 10−2	33.71	39.66	35.14
No Hole, No Shell (No Groove)	15.63	1.87 × 10−5	3.76 × 10−2	10.93	7.47	7.43
With Hole, With Shell (No Groove)	14.01	1.72 × 10−5	3.45 × 10−2	−0.57	−1.15	−1.43
With hole, no shell (No Groove)	14.09	1.74 × 10−5	3.49 × 10−2	0.0	0.0	0.0
No Hole, With Shell (No Groove)	15.63	1.87 × 10−5	3.75 × 10−2	10.93	7.47	5.71

provide a comprehensive summary of Von Mises stress, average deformation, and average strain across all eight design configurations, shedding light on the influence of grooves, shells, and holes on structural performance. In Table 2, under the “without groove” category, the model with a hole and no shell exhibited the lowest Von Mises stress at 0.296 MPa. This represents a significant improvement over the “with groove” category, particularly the no-hole, no-shell model, which recorded the highest stress at 0.586 MPa. Additionally, the model with both a hole and a shell, also under the “without groove” category, demonstrated similarly low stress at 0.299 MPa, reinforcing the conclusion that the removal of grooves plays a dominant role in reducing internal stress, even when a shell is present. Although the model with a hole and no shell under the “with groove” category showed the lowest average deformation in Table 2, it also registered a relatively high average stress of 0.355 MPa. This indicates a trade-off in designs with grooves, where reduced deformation may come at the expense of higher internal stress concentrations. Table 2 and Table 3 also show that the models under the “without groove” category—specifically those with a hole and either with or without a shell—exhibited the lowest average deformation values, with 14.01 µm for the shell-included model and 14.09 µm for the model without a shell. These results suggest that the absence of grooves significantly improves structural stability, with shell presence offering modest additional reinforcement. Similarly, average strain values were lowest in these same groove-free configurations. The model with a hole and shell recorded an average strain of 1.72 × 10⁻⁵ µm/µm, closely followed by the hole and no shell model at 1.74 × 10⁻⁵ µm/µm. These values contrast sharply with the no-hole, no-shell model under the “with groove” category, which exhibited significantly higher strain, reinforcing the conclusion that groove removal is essential to reducing internal strain. Although grooves are conventionally incorporated to support anatomical features such as alignment, balance, and interface flexibility, this research reveals that they introduce stress concentrations that compromise structural performance. The presence of grooves disrupts continuous load paths, leading to elevated stress and strain. In contrast, groove-free designs benefit from uninterrupted load distribution, resulting in superior mechanical behavior, especially when supported internally by shells. Overall, the shell consistently contributed to improved stress and strain responses across all configurations, aligning with the understanding that it aids in distributing loads and increasing stiffness. However, the removal of the groove proved to be the most critical factor in enhancing structural efficiency. Based on the collective data, the design featuring a hole and shell without a groove emerged as the most mechanically optimal configuration, striking an effective balance between flexibility, strength, and manufacturability—particularly suited for ball-strike 3D-printed prosthetics.

Table 4. Performance Comparison of Best vs. Worst Prosthetic Design.

Metric	Worst Design (No Hole, No Shell—Groove, Design 1)	Best Design (With Hole, No Shell—No Groove, Design 7)	Improvement %
Max Total Deformation (µm)	120.63	64.81	46.3%
Max Equivalent Strain (µm/µm)	2.79 × 10−4	1.43 × 10−4	48.7%
Max Stress (MPa)	0.586	0.296	49.5%
Avg Deformation (µm)	25.13	14.09	44.0%
Avg Strain (µm/µm)	2.90 × 10−5	1.74 × 10−5	40.0%
Avg Stress (MPa)	5.67 × 10−2	3.49 × 10−2	38.4%

shows the performance comparison of best vs. worst prosthetic designs.

In Figure 11, the bar graph shows the comparison of maximum values of Von Mises stress in all 8 prosthesis designs. In terms of groove-included designs (Designs 1–4), stresses in Design 1 and Design 2 are highest among the designs at 0.586 and 0.573 MPa, respectively, which shows that stress concentration is significant with the introduction of grooves. As the moderate stress of 0.453 MPa in Design 4 indicates, the shell, although it partially neutralizes the negative effect of the grooves, does not reconcile it completely. The designs without grooves (Designs 5–8) show a significant reduction in the value of stress, though of them, Design 6 and Design 7 hold the least stress of 0.299 MPa and 0.296 MPa, respectively. Design 7 in green is the best configuration, which consists of a hole and shell with no grooves and is found to have the least value of maximum stress as compared to the rest of the designs.

In Figure 12, Designs 5, 6, and 7 show the lowest values in terms of maximum total deformation, which implies that these designs are stronger and structurally more stable than the other designs. Design 5 has the lowest deformation at 64.78 μm, followed by Design 6 (64.805 μm) and Design 7 (64.808 μm), with the difference between them being negligible. Design 8 has a little higher deformation of 66.77 μm, with the groove-based designs (1–4) generally performing worse in this measure, with Design 1 (120.63 μm) and Design 2 (120.56 μm) almost doubling the deformation of the best performers. This implies that the no-groove designs, particularly Designs 5, 6, and 7, have much higher displacement resistance under load.

Figure 13 illustrates the maximum equivalent elastic strain. The lowest values are found in Design 7 (1.43 × 10⁻⁴) and Design 6 (1.47 × 10⁻⁴), which means that Design 7 and Design 6 are more resistant to elastic deformation and, therefore, under loading conditions. Design 5 and Design 8 are close behind at 1.67 × 10⁻⁴, and the groove-based designs typically have higher strain values, with Design 1 (2.79 × 10⁻⁴) and Design 2 (2.77 × 10⁻⁴) performing worst in this measure. Design 3 (1.70 × 10⁻⁴) and Design 4 (2.18 × 10⁻⁴) are in the middle. Overall, the no-groove designs, especially Design 7 and Design 6, exhibit the best strain behavior and are therefore better suited to applications where structural integrity over a long period is a consideration.

In all three key performance parameters, namely maximum total deformation, maximum equivalent elastic strain, and maximum equivalent stress, Design 7 ranked as one of the best-performing configurations and, therefore, the most balanced and structurally efficient one. With regard to maximum total deformation, Design 7 (64.808 μm) is nearly equal to Designs 5 and 6 in terms of minimum displacement under load, which implies an outstanding stiffness and structural resistance to deflection. This low deformation guarantees stability of the dimensions, which is very important to guarantee functional performance under practical applications. In the analysis of maximum equivalent elastic strain, design 7 is the first to be considered, with the least strain recorded (1.43 × 10⁻⁴). It implies that it experiences the least elastic strain, and this directly leads to improved durability and service life due to the minimization of the possibility of fatigue damage as a result of the repeated loading cycles. Design 7 gives the lowest value of maximum equivalent stress (0.296 MPa), slightly better than Design 6 (0.299 MPa). Reduced stress means improved stress distribution within the structure, minimizing the possibility of crack initiation or highly localized points of failure. The fact that it has the least deformation, the lowest strain, and the lowest stress value definitely makes Design 7 the most mechanically efficient configuration. It is superior in stiffness without loss of strength and durability, and thus the best option where structural reliability, longevity, and load resistance are of primary concern.

Despite these insights, the study is limited by its reliance on computational models without experimental validation, simplified assumptions of material properties, and a narrow set of design configurations, which may constrain generalizability. Future work should therefore focus on experimental testing, broader exploration of geometric and material variations, and detailed analysis of interactions between groove dimensions, shell thickness, and material anisotropy to refine design guidelines and strengthen the applicability of these findings in practical scenarios.

4. Conclusions

This paper highlights the powerful synergy between analytical engineering methods and additive manufacturing in the development of advanced 3D-printed prosthetic limbs. Through a detailed finite element analysis (FEA) of eight distinct design configurations, the study evaluates how specific geometric features—namely grooves, internal shell reinforcements, and perforations (holes)—influence the mechanical performance of prosthetic components. The investigation reveals that these design parameters play a crucial role in determining structural behavior under load, particularly in terms of stress distribution, elastic strain, and deformation resistance. Among all tested models, the configuration featuring both a hole and an internal shell, but without a groove, consistently demonstrated superior mechanical efficiency. This design achieved the lowest levels of Von Mises stress, elastic strain, and total deformation, indicating enhanced stiffness, structural integrity, and overall performance. The absence of grooves allowed for continuous load paths and minimized stress concentrations, while the internal shell helped distribute applied forces more effectively, further boosting stability. These results reinforce the importance of carefully optimizing structural geometry when designing prosthetic limbs—especially those subjected to dynamic or repetitive forces such as in animal movement. Not only do the findings contribute to our understanding of how internal and external features interact mechanically, but they also suggest that biomechanical comfort, safety, and functionality can be significantly improved through informed design strategies supported by simulation. Ultimately, this work supports the development of more robust, lightweight, and user-friendly 3D-printed prosthetic limbs for animal rehabilitation, offering a cost-effective and customizable alternative to conventional prosthetic solutions. This study was conducted on static loading; however, prosthetic limbs in real-life experience dynamic and cyclic loads during locomotion, which can be more than body weight. These kinds of loads can influence stress distribution, fatigue behavior, and long-term performance. To overcome these limitations in the future, the performance would be tested under repetitive loading by implementing transient FEA and gait analysis to ascertain reliability in real-world applications. Although the benefits of 3D printing in veterinary practice are undeniable, there are still obstacles connected with the selection of materials that are durable and biocompatible. The use of newer materials, including resorbable polymers and metal alloys, has long-term effects that are not yet fully understood, and regulatory and ethical issues also complicate their use. The next step of this project will be the manufacture of the optimized version and the mechanical testing to verify the simulations in real conditions.