Session: 02-01-06: 7th Annual Conference-Wide Symposium on Additive Manufacturing: Unique Applications II

Paper Number: 99926

99926 - Novel Multi-Material Additively Manufactured Energy Absorptive Tensegrity Structures 

Traumatic Brain Injury (TBI) is a serious health issue that can result from ballistic and blast impacts, and sudden accelerative/decelerative motions such as concussion, car accidents etc. TBI is prevalent among former military members because of head injuries trauma sustained in combat. There are many difficulties associated with quantifying and understanding brain damage which result in difficulties in understanding how to protect against it. There is no clear threshold or acceleration limits to define when damage will occur within the brain. Instead, TBI is dependent on many different factors and can occur from a wide variety of impacts. TBI can be mild to severe and appear in the forms of memory loss, irregular moods, as well as the loss of other cognitive functions.  As a result, the goal when creating combat helmets, the goal is to improve energy absorption levels as much as possible to help minimize the probability of brain injury. Advancements in the field of additive manufacturing and 3D printing have allowed for the creation of new design opportunities for helmets, many of which were previously inaccessible. Additive manufacturing separates itself from traditional manufacturing methods is in its ability to create extremely complex shapes, incorporate multiple materials into a singular design, and simplify assemblies into one part.  As a result, new approaches can be created for how to create an energy absorption system. Cellular structures have a high strength to weight ratio, can experience large deformations, and are customizable to meet specific needs, all of which help improve energy absorption. However, when fracture occurs, the structure is no longer being stressed and thus, no longer absorbs energy. To combat this issue, tensegrity structures can be utilized to extend the time to failure. Tensegrity structures are made of both rigid and flexible load bearing members which are arranged in a way that maximizes strength and flexibility while resisting failure. These parameters directly affect energy absorption capabilities of a structure and provide opportunities for improvement over traditional single material cellular designs. Furthermore, Stratasys has created their own proprietary materials to be used in their Polyjet technology printers, one of them being a rigid polymer with good strength and another being a flexible rubber with high flexibility to provide material options with vastly different properties. The Stratasys J850 Pro enables the user to select any two of the stock Stratsys materials and mix desired concentrations of each material together to create a hybrid material that is semi rigid and semi soft with its own unique properties. This allows full control over material properties such as strain limit, which can be adjusted from around 10% to over 200% under loading based upon the selected ratio of rigid and flexible polymers. With the ability to use multiple materials and tailor them to design needs, tensegrity structures can be combined into cellular design to maximize energy absorption without any of the design restrictions present in current helmets. This allows geometry and material properties to be uniquely selected and constructed in a way to maximize energy absorption.

Presenting Author: Justin Marino University of Texas at Arlington

Presenting Author Biography: Mr. Justin Marino is a student is a graduate student working towards an M.S. Degree in the Mechanical and Aerospace Engineering Department at the University of Texas at Arlington. His research is part of a larger scale collaborative effort at the Multi Scale Mechanics and Physics Lab led by Dr. Ashfaq Adnan to gain understanding of Traumatic Brain Injury and how to protect against it. Specifically, Mr. Marino is tasked with researching the mechanics and energy absorption capabilities of additively manufactured cellular structures and their applications in combat helmets to prevent TBI. Before joining the graduate program, Mr. Marino completed his B.S. in Mechanical Engineering at the University of Texas at Arlington graduating with honors. During this time, he worked with the UTA Racing Team to help develop a competition winning racecar and participated in NCAA Div. I Athletics representing the university as a member of the baseball team.

Authors:

Justin Marino University of Texas at Arlington
Layth Ahmad The University of Texas at Arlington
Lauren Hutchison The University of Texas at Arlington
Ashfaq Adnan The University of Texas at Arlington