The Johns Hopkins University

Andrew C Merkle

Jack C Roberts

Catherine M Carneal

Jeffrey M Paulson

Liming M Voo

Matthew S Johannes

Craig B Leese

Ian D Wing

Bliss G Carkhuff

Morgana M Trexler

Steven M Storck

David M VanWie

Matthew G Bevan

Vanessa D Alphonse

Ibolja Cernak

Howard A Conner

Quang T Luong

Mark A Athey

Kathleen M Perrino

A system provided herein may be configured to evaluate helmet performance. The system may include an impact assembly that includes a stationary post operably coupled to one or more stationary load cells and a plurality of modular headforms. Each modular headform may include a first side and a second side configured to lock together around the impact assembly and receive a helmet. The modular headform may determine a position of the helmet relative to the one or more stationary load cells. Furthermore, the one or more stationary load cells may be configured to measure impact force at a position where one of the plurality of the modular headforms are operably coupled to the impact assembly. Additionally, each of the plurality of modular headforms correspond to a position in relation to the impact assembly to measure the impact force to the one or more load cells at a predefined number of impact locations on the helmet to evaluate the performance of the helmet.

System and method for evaluation of helmet performance

A surrogate multilayered material and manufacturing method thereof includes a first fiber reinforced layer, the first reinforced layer including a crosslinked polymer and fibers, and a second fiber reinforced layer, the second reinforced layer including the crosslinked polymer and the fibers. A foam layer is disposed between the first and second fiber reinforced layers. Opposite faces of the foam layer are in direct contact with the first fiber reinforced layer and the second fiber reinforced layer. The foam layer has a compressive strength of about 3.5 to about 4.5 MPa, when measured as per ASTM-D-1621-73, and a shear strength of 1.50 to about 2.15 MPa, when measured as per ASTM-C-273.

Cranial bone surrogate and methods of manufacture thereof

A surrogate multilayered material includes a first fiber reinforced layer; the first reinforced layer including a crosslinked polymer and fibers; a second fiber reinforced layer; the second reinforced layer including the crosslinked polymer and the fibers; a foam layer; the foam layer disposed between the first fiber reinforced layer and the second fiber reinforced layer; where opposite faces of the foam layer are in direct contact with the first fiber reinforced layer and the second fiber reinforced layer; the foam layer having a compressive strength of about 3.5 to about 4.5 MPa, when measured as per ASTM-D-1621-73, and a shear strength of 1.50 to about 2.15 MPa, when measured as per ASTM-C-273.

A human surrogate neck model includes a spinal neck region containing cervical vertebrae. A biosimulant intervertebral material is inserted between the cervical vertebrae. The spinal neck region is surrounded by a first silicone material mixed with a polymeric cross-linking inhibitor. One or more elastic tension bands are anchored to a top interface and a bottom interface of the neck model. A second silicone material mixed with a polymeric cross-linking inhibitor is applied to surround the spinal neck region and the first silicone material and to embed the tension bands. One or more of the elastic tension bands and/or a concentration ratio of the first silicone material or second silicone material to the polymeric cross-linking inhibitor can be adjusted for variable test conditions to closely simulate or mimic the static and dynamic characteristics of a human neck in various scenarios.

Human surrogate neck model

A blast tube includes three portions and three diaphragms. The first portion has a first length and a first cross section. The second portion has a second length and a second cross section. The third portion has a third length and a third cross section. The first diaphragm is disposed between the second portion and the third portion and switches from a closed state to an open state at a first time. The second diaphragm switches from a closed state to an open state at a second time after the first time. The third diaphragm is disposed between the first portion and the second portion and switches from a closed state to an open state at a third time after the second time. The third portion is disposed between the first diaphragm and the second diaphragm.

System and method for simulating primary and secondary blast

A human surrogate head model (HSHM) to measure brain/skull displacement due to a physical force, such as due to an explosive, ballistic, or automotive crash type of event. A HSHM may include a plurality of magnetic field generators positioned stationary relative to a HSHM skull, each to generate a magnetic field oriented with respect to a corresponding one of multiple directions. The HSHM may include one or more electromagnetic force (EMF)-based displacement sensors, each of which may include three inductive coils oriented orthogonally with respect to one another and co-aligned about a central point. A signal processor may be implemented to separate signals generated by each coil of each EMF-based displacement sensor into a plurality of component magnitudes, each attributable to a corresponding one of the magnetic fields. A computer-implemented model may be implemented to correlate between the component magnitudes and a corresponding position and orientation of the displacement sensor.

Methods and systems to implement a surrogate head model and directly measure brain/skull relative displacement

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Gaithersburg, MD, United States of America

Andrew C Merkle