Bhargav Visconti

5 MIN READ

The introduction of orthopedic grips in the early nineteenth century revolutionized fencing by offering a grip specially contoured to fit the hand. However, in the last 200 hundred years there have been few improvements made upon the early designs, such as the Visconti grip.

The Bhargav Visconti aims to elevate fencing performance by utilizing modern manufacturing and design technologies to further enhance and optimize the fencing grip. With advancements in material science significantly reducing the weight of most modern blades, it has become increasingly feasible—as well as increasingly desirable—to reduce grip weights while still maintaining proper blade balance.

Leon Paul, a premier manufacturer of fencing gear known for their design innovation, produces a light-weighted titanium pistol grip known as the “Sub Zer0.” The release of their initial batch of grips coincided with when I took a class with Dr. Joe Beaman, one of the inventors of selective laser sintering (SLS) additive manufacturing. For this reason, I was initially incredibly excited to see such innovation in the sport I love.

However, their design seems to be incredibly primitive. They clearly have not used topology optimization, which I believe is a greatly missed opportunity since additive manufacturing is so conducive to unique geometry. It also suggested to me that they probably ran minimal finite element analysis and their design would be prone to failure.

All of this lead me to conclude that the Sub Zer0 was an interesting novelty, but not a legitimate solution. I sought to create a better design, that could genuinely be useful in fencing.

Finite Element Analysis

There are two primary loads that the grip will regularly endure: the force exerted by someone holding the sword and the force from being bolted to the blade. Due to the unique geometry of the fencing grip, it is challenging to accurately perform an FEA analysis that accounts for human grip force. The maximum recorded human grip strength is 150 kg, or approximately 1500 N. I estimated all the regions where pressure would be applied while holding the blade during a bout and chose to apply 2000 N uniformly across the area.

This overestimation, by a factor of 1.33, was intended to account for any non-uniform pressure distribution. However, I acknowledge that this is not a rigorously scientific approach. The force from being bolted down to the blade was rather easy to calculate.

Material selection is also very important when running both finite element analysis topology optimization. Read more about the thought behind the material in the Material Selection section.

Topology Optomization

After applying all the loads to the model and conducting finite element analysis, I proceeded with the topology optimization. As outlined in the Goals & Constraints section, the objective was to remove as much material as possible while maintaining at least 95% of the original stiffness. Over 60% of the material was successfully removed, leaving us with a highly optimized inner shell. Many regions effectively transformed into pipe-like structures, which makes sense given the strength of pipes under compressive loads.

By nature of doing such a design and choosing to use SLS to print it, we assume that the topology optimization is correct. I would like to do design validation, but considering the cost, it would be rather difficult.

Latticing/Lightweighting

A Voronoi surface lattice was employed to further reduce the weight of the grip while preserving the traditional Visconti shape for the overall outline. Special care was taken to ensure the lattice remained uniform, preventing any regions of unusually high or low stress if subjected to loads.

The decision to incorporate a lattice was also driven by ergonomic considerations. It seems that right now the pursuit of "more grip" is hard to satisfy. Significant advancements have been made in grip technology for fencing gloves, as well as many fencers using tennis tape to increase friction on the grip surface. I believed that a lattice structure would achieve a similar effect as well.

The choice of a Voronoi lattice, in particular, was due to its 'organic' appearance. Given that topology optimization is often likened to natural, organic shapes, I felt it was a fitting choice.

Final Geometry

The lattice exterior shell and optimized interior shell were combined together to produce the final geometry.

I ruled out Titanium very early, even though that is what Leon Paul used. We shall infer that Leon Paul chose to use Ti-6Al-4V. In my opinion, the fatal flaw in Leon Paul's design is that their light-weighting lattice carries load. A lattice shell is purely for aesthetic purposes and is not suitable to carry load. This is because they are essentially thin and randomly oriented rods. This will cause concentrations of stress in components unsuitable to carry them. This is why I believe Leon Paul chose to use Titanium, since they would need a tremendously high yield stress for their design not to fail.

Since my design uses topology optimization to create an inner geometry that carries most, if not all, of the load, I assumed I did not have to worry too much about the tensile yield stress in so far as whether the grip will fail. What I did look at was how much material I would be left with depending on the specific materials I used.

The choice was between some type of aluminum or nylon 12. I wanted to print at least two grips, but the vendors I researched quoted around $130 to print a single grip in aluminum based on my design. However, it was only about $30-50 to print them in nylon 12, depending on the type.

I chose to use 30% Glass Fiber Filled Nylon 12 because it resulted in a negligible increase in density but a x2.19 increase in tensile yield stress. For an order of two grips, I was charged $53 per unit. However, if I were to order even just 10, the price would drop to about $30 per.

I have yet to decide what other components I am going to use to put this grip in a blade such that it will be properly balanced, but after I have made those decisions I shall buy the parts and try to test the sword in a bouting condition.

After receiving feedback on the design, I plan to create a second version. For this iteration, I will move away from the Visconti base design and develop my own profile.

To create this new profile, I will craft several options out of clay and seek input from members of the University of Texas Fencing Team, where I serve as the Epee captain, to determine the most promising design.