03/30/2026
By Danielle Fretwell

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a Master's Thesis defense by Sanmeel Vijay Lagad on: "A Biofidelic Approach to Measuring Bending Stiffness in Carbon-Fiber Reinforced Footwear and Insoles."

Candidate Name: Sanmeel Vijay Lagad
Degree: Master’s
Defense Date: Thursday, April 2, 2026
Time: 3 - 4:30 p.m.
Location: Falmouth Hall 313

Committee:

  • Advisor: Scott Stapleton, Professor, Mechanical and Industrial Engineering, University of Massachusetts Lowell
  • Tanner Thorsen, Assistant Professor, Kinesiology and Nutrition, University of Southern Mississippi
  • Alireza Amirkizi, Professor, Mechanical Engineering, University of Massachusetts Lowell

Brief Abstract:
Footwear does more than protect the foot. It also changes how the body moves, how forces are transferred during walking, and how stiff or flexible a boot feels to the wearer. This is especially important in performance and tactical footwear, where bending stiffness can influence comfort, fatigue, energy return, and risk of injury. Carbon-fiber reinforcements and stiff insoles are increasingly being used in these applications, but current mechanical tests do not fully capture how stiff a boot actually feels during human movement.

Traditional footwear bending tests, such as three-point bending, mainly measure how the sole bends under a simplified laboratory setup. These methods are useful and repeatable, but they do not account for the way the foot bends inside the boot during gait, and they do not include the contribution of the boot upper to the overall bending response. As a result, they may underestimate the stiffness experienced by the user.

This study developed a new biofidelic testing method designed to better represent how a boot bends during walking. The method was based on human gait analysis and focused on bending about the first metatarsophalangeal (MTP) joint, the main location where the forefoot bends during push-off. A 3D-printed foot surrogate was inserted into the boot, and the boot was loaded in a way that reproduced the motion profile observed in gait. This made it possible to measure not only the bending response of the sole, but also the contribution of the full boot structure, including the upper.

Desert combat boots were tested with three insole conditions: the manufacturer-provided insole, a medium-stiffness carbon-fiber insole, and a high-stiffness carbon-fiber insole. Results from the new biofidelic method were compared with results from a traditional three-point bending test. Both methods showed that stiffer insoles increased boot stiffness. However, the biofidelic method consistently measured higher stiffness values than the three-point bending test, indicating that it captured additional structural contributions that traditional testing does not. The biofidelic method also measured mechanical energy return, showing that carbon-fiber insoles increased the amount of energy returned during unloading.

The main outcome of this work is the introduction of Effective Bending Stiffness (EBS), a more complete measure of the stiffness experienced by the wearer during gait-relevant boot bending. This study shows that footwear bending stiffness is not determined by the sole alone, and that upper construction can make a significant contribution to the effective stiffness of the boot. The proposed method offers a practical new way to evaluate footwear in a manner that is more relevant to real use, with potential applications in military, occupational, and performance footwear design.