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Technical Paper

Human Foot-Ankle Injuries and Associated Risk Curves from Under Body Blast Loading Conditions

Under body blast (UBB) loading to military transport vehicles is known to cause foot-ankle fractures to occupants due to energy transfer from the vehicle floor to the feet of the soldier. The soldier posture, the proximity of the event with respect to the soldier, the personal protective equipment (PPE) and age/sex of the soldier are some variables that can influence injury severity and injury patterns. Recently conducted experiments to simulate the loading environment to the human foot/ankle in UBB events (~5ms rise time) with variables such as posture, age and PPE were used for the current study. The objective of this study was to determine statistically if these variables affected the primary injury predictors, and develop injury risk curves. Fifty below-knee post mortem human surrogate (PMHS) legs were used for statistical analysis. Injuries to specimens involved isolated and multiple fractures of varying severity.
Journal Article

Optimization of Pneumatic Network Actuators with Isosceles Trapezoidal Chambers

Abstract Soft actuators with pneumatic network have innovative potential applications in medical and rehabilitation areas. The performance of this kind of actuators is determined by the design of chambers and the properties of the active extensible layer and the passive inextensible layer. In this article, actuator with isosceles trapezoidal chambers is proposed. Orthogonal experiment design and finite element method are used to optimize the structure of actuators. Results indicate that adding constrain-limiting paper in the passive layer can significantly reduce the bending radius. Position of the paper in the passive layer also affects the bending radius. Actuators with trapezoidal chambers can have a smaller bending radius compared with that with rectangle chambers. The bending radius decreases as the ratio of short base to long base of trapezoid decreases. Increasing the number density of chambers can further reduce the bending radius.
Training / Education

FEA Beyond Basics: Nonlinear Analysis Web Seminar RePlay

Finite Element Analysis (FEA) has been an indispensable tool for design simulation for several decades but this wide spread use has been limited to simple types of analyses. Relatively recently, more advanced analyses have given easy-to-use interfaces enabling design engineers to simulate problems formerly reserved for analysts. FEA Beyond Basics targets the FEA users who wish to explore those advanced analysis capabilities. It will demonstrate how to move past the ubiquitous linear structural analysis and solve structural nonlinear problems characterized by nonlinear material, large displacements, buckling or nonlinear connectors.

Tech Briefs: April 2018

Laser Detecting Systems Enhancing Survivability and Lethality on the Battlefield Designing With Plastics for Military Equipment Engine Air-Brakes Paving the Way to Quieter Aircraft Nett Warrior Enhancing Battlefield Connectivity and Communications XPONENTIAL 2018 - An AUVSI Experience Communications in Space: A Deep Subject First Air-Worthy Metal-Printed RF Filter Ready for Takeoff Validation of Automated Prediction of Blood Product Needs Algorithm Processing Continuous Non-Invasive Vital Signs Streams (ONPOINT4) Using a combination of non-invasive sensors, advanced algorithms, and instruments built for combat medics could reduce hemorrhaging and improve survival rates. Calculation of Weapon Platform Attitude and Cant Using Available Sensor Feedback Successful development of mobile weapon systems must incorporate operation on sloped terrain.
Technical Paper

Development and Calibration of the Large Omnidirectional Child ATD Head Finite Element Model

To improve the biofidelity of the currently available Hybrid III 10-year-old (HIII-10C) Anthropomorphic Test Device (ATD), the National Highway Traffic Safety Administration (NHTSA) has developed the Large Omnidirectional Child (LODC) ATD. The LODC head is a redesigned HIII-10C head with mass properties and modified skin material required to match pediatric biomechanical impact response targets from the literature. A dynamic, nonlinear finite element (FE) model of the LODC head has been developed using the mesh generating tool Hypermesh based on the three-dimensional CAD model. The material data, contact definitions, and initial conditions are defined in LS-PrePost and converted to LS-Dyna solver input format. The aluminum head skull is stiff relative to head flesh material and was thus modeled as a rigid material. For the actual LODC, the head flesh is form fit onto the skull and held in place through contact friction.
Training / Education

Fundamentals of GD&T ASME Y14.5M 1994 - Advanced Level

This 3-day advanced-level Fundamentals of GD&T course is an in-depth study of the terms, rules, symbols, and concepts of geometric dimensioning and tolerancing as prescribed in the ASME Y14.5M-1994 Standard. The course can be conducted in three 8-hour sessions or with flexible scheduling including five mornings or five afternoons.  This class includes all the content from the Fundamentals of GD&T 2-day foundational course: an explanation of geometric symbols, including each symbol’s requirements, tolerance zones, and limitations.
Training / Education

Fundamentals of GD&T for Inspectors - Foundational Level

This 2-day foundational-level course builds on geometric dimensioning and tolerancing fundamentals and teaches an introduction of how to inspect GD&T requirements.  The course offers an explanation of the geometric symbols, rules, and concepts, the datum system, and how to inspect GD&T requirements using tools from the four categories of inspection tools (CMM; comparison instruments and fixed gages; hand tools and open set up; and production gaging systems).
Training / Education

Fundamentals of GD&T ASME Y14.5 - 2009 Advanced Level

This 3-day Fundamentals of GD&T course provides an in-depth study of the terms, rules, symbols, and concepts of geometric dimensioning and tolerancing, as prescribed in the ASME Y14.5-2009 Standard. The course can be conducted in three 8-hour sessions or with flexible scheduling including five mornings or five afternoons. 
Training / Education

Applications of GD&T ASME 14.5 - 1994 & 2009 Foundational Level

This two-day foundational-level course teaches the thought processes involved in assigning GD&T to components, and it changes the way many engineers think about part tolerancing. The course focuses on what constitutes good and poor drawing practices, common dimensioning methods used in industry, using GD&T to communicate system functions on component dimensions, and the logic of how to apply GD&T to components. You’ll also learn how to select datum features and how to fully define component surfaces using GD&T. Establishing tolerance values is not covered.
Training / Education

Advanced Concepts of GD&T Foundational Level

This two-day foundational-level course teaches Advanced Concepts of GD&T as prescribed in the ASME Y14.5-2009 Standard. It offers an explanation of complex GD&T topics, such as the expanded use of composite position and profile tolerances, customized datum reference frames, the translation modifier, and applying GD&T to non-rigid parts. You’ll learn about functional dimensioning, form controls, the datum system, additional and complex datum feature types, expanded datum target concepts and usage on restrained parts, simultaneous, and separate requirements.
Training / Education

Model-Based Systems Engineering (MBSE)

This seminar is offered in China only and presented in Mandarin Chinese. The course materials are bilingual (English and Chinese). As the complexity of products increases, traditional text-based systems engineering can no longer meet the needs. To solve the problem, Model-based Systems Engineering offers a unified communication platform among relevant staff by carrying out diagram-based unambiguous description, analysis and design for the demand, structure and behavior of complex systems in the form of a model.
Training / Education

Critical Concepts of Tolerance Stacks ASME Y14.5 -1994 & 2009 Advanced Level

This 3-day advanced-level course provides an in-depth explanation of how to use tolerance stacks to analyze product designs and how to use geometric tolerances in stacks. The course can be conducted in three eight-hour sessions or with flexible scheduling, including five mornings or five afternoons.  You’ll learn the essential methods and concepts used for creating 1D part and assembly tolerance stacks. The course discusses how virtual condition affects part assembly, stack methods, and using the stack form and spreadsheet.
Training / Education

Fundamentals of Fatigue Analysis

Fatigue is a structural failure mode that must be recognized and understood to develop products that meet life cycle durability requirements. In the age of lightweighting, fatigue strength is an important vehicle design requirement as engineers struggle to meet stringent weight constraints without adversely impacting durability. This technical concept course introduces the fatigue failure mode and analysis methods. It explains the physics of material fatigue, including damage accumulation that may progress to product failure over time, and it provides the needed foundation to develop effective fatigue prediction capabilities.