Saddle up

	This suspension saddle system, designed by Valentina Baio '09, should help prolong a horse's active life.

Inside a barn that stands in rolling hill country 10 miles west of Lehigh, Valentina Baio ’09 brushes dust and bits of molting winter fur from her 16-year-old thoroughbred Armani.
She can’t help but notice how the years have changed her horse.
“He’s a lot more affectionate now than he used to be,” says Baio, scratching the gelding in a sweet spot behind his left ear. “He likes to be groomed. He rubs you back when you pet him.”
Armani’s neck and his face still sport a few patches of black, remnants of the bygone days of his youth when he raced and showed. The rest of his coat is mellowing into a dark bay. Baio steps around to Armani’s side and examines the droop behind his shoulders.
“His back has dipped in the last few years,” she says. “He used to be straighter from his withers to his back end.”
Age takes its toll on even the fittest horse, but Baio, who recently completed a B.S. in mechanical engineering at Lehigh, wonders if the standard leather saddle doesn’t accelerate the process.
To an engineer, says Baio, a horse’s back and spine can be compared to a beam as it bends. As a horse canters, moving at a pace faster than a trot but slower than a gallop, the rider’s weight pushes down on the horse and causes its back to curve, or bend. This high “bending moment” can, after years of riding, cause the horse to sustain permanent damage, and it can hasten the day when a horse is no longer able to ride. Horses live 25 to 35 years, Baio says, but they are seldom able to canter and jump past their 22nd or 23rd birthday.
Baio, hoping to prolong a horse’s active life, is designing a suspension saddle system made of carbon fiber or another lightweight composite material that will reduce the bending moment on the horse’s spine. It will accomplish this by spreading the rider’s weight closer to the four legs of the horse and by using a spring and damper to reduce the impact force between rider and horse.
The idea for the project came from Joachim Grenestedt, professor of mechanical engineering and mechanics, who has fabricated high-speed boats, airplanes, a land speed racer and other structures made of lightweight composite materials.
“For a horse not to have a suspended saddle does not make much sense to me,” says Grenestedt, who predicts suspended saddles are the wave of the future. “The forces on the rider and on the horse are unnecessarily high. I believe the bending moments on the horse’s back can be reduced by a factor of between three and ten.”
Baio designed the suspension saddle system and built a wooden prototype in a one-semester independent study class taught by Grenestedt. She will continue the project, fabricating and testing a model of the saddle and marketing the final product, while studying for an M.S. in mechanical engineering at Lehigh over the next two years.
Equestrian and engineer
Valentina Baio was still a toddler, her parents tell her, when she insisted on riding every pony at every carnival she went to. When she could form sentences, she began begging for riding lessons. When she was six, she enrolled at the Thorncroft Equestrian Center in Malvern, Pa. When she was 13, her parents bought Armani, who had recently retired from racing.
Armani arrived just as Baio’s fortunes at school were improving.
“In middle school, I was horrible at math. But in eighth grade, I had the best math teacher in the world. She gave me extra work and met outside class with me.
“In high school, I took all the accelerated math courses. I was fascinated with math and physics and I discovered I was good at them. My Calculus II teacher told me I should consider engineering.”
At Lehigh, Baio joined the Formula SAE (Society of Automotive Engineers) Club, which builds racecars for student competitions. She was a teaching assistant in the mechanical engineering department’s junior-level manufacturing course. And she completed a second independent study project investigating nanofluids that improve heat transfer.

	Valentina Baio ’09, aboard her thoroughbred Armani in the horse's younger days.

Her interest in composite lightweight materials began in 2008 when Grenestedt suggested she try designing a lightweight suspension saddle that would reduce the load on a horse’s spine and still accommodate a horse’s body movements as well as a leather saddle does. Grenestedt had thought of the idea two years earlier and had drafted several possible designs before handing the project off to Baio.
The project requires knowledge not only of engineering but also of a horse’s movements, the interactions of horse and rider, and the response of the saddle to the movements of horse and rider.
To reduce the impact of rider and saddle on the horse’s spine, Baio has enlarged and elongated the saddle to make it sit on the outer edges of the horse’s back. This serves to reduce the bending moment imposed on the horse’s spine.
The front of Baio’s saddle slopes up to form a gooseneck, which transfers the weight of the rider into a single shock absorber positioned directly beneath the top of the gooseneck. Baio took the shock absorber from a mountain bike and the saddle seat, for the time being, from a unicycle.
It took Baio a month and a half to design a prototype of the saddle. She used a CAD (computer-aided design) software called SolidWorks along with finite-element analysis software and hand calculations to design the gooseneck, to determine the optimum thickness of the tubes connecting the saddle seat to the saddle frame, and to optimize the structure.
“The gooseneck required a lot of tweaking. And I went from two shock absorbers to one. I had to calculate the spring rate, stroke and motion ratio of the suspension. Right now I’m using a 400 pound/inches spring, but I may need to reduce that to 300.”
Baio made her prototype of layers of plywood because it is cheap and easy to work with. She calculated the optimum outline and dimensions, cut the plywood sections with a waterjet cutter, and then glued them together.
A pressure-point proof
Her next step will be to determine the optimum material—carbon fiber or fiberglass—and the optimum number of layers for the support frame of the saddle. She also wants to redesign the suspension system to optimize the movement of the saddle and to reduce the amount of load being placed horizontally on the frame.
Then she will test the new saddle on Armani. Her plan is to place her saddle atop a mattress-like material fitted with pressure points, or sensors, and ride the horse. Then she will repeat the procedure using a standard saddle, and compare the performances of the two saddles, as measured by the sensors.
Back in the barn, Baio finishes grooming Armani and prepares to take him around the inside track and its two-foot hurdles.
Her visits to the barn, she says, are “bittersweet” for the horse.
“He’s always happy to see me, but he