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Journal Article

Optimization of Pneumatic Network Actuators with Isosceles Trapezoidal Chambers

2019-10-04
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.
Technical Paper

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

2017-11-13
2017-22-0006
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.
Training / Education

FEA Beyond Basics: Nonlinear Analysis Web Seminar RePlay

Anytime
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.
Training / Education

Introduction to Statistical Tolerance Stacks 1-day

This course is an introduction to statistical tolerance stacks, a crucial skill in today's competitive workplace. Utilizing the expertise of world-renowned GD&T expert Alex Krulikowski, the course includes a brief overview of several terms used in statistical stacks. It explains four methods for applying statistics to tolerance stacks and covers precautions about when and how to use statistics in stacks. Newly acquired learning is reinforced throughout the class with stacks that allow the student to practice applying statistical methods.
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.
Training / Education

Critical Concepts of Tolerance Stacks 2009 3-day

2021-07-13
This course, based on the ASME Y14.5-2009 standard, provides an in-depth explanation of how to use tolerance stacks to analyze product designs and how to use geometric tolerances in stacks. You will learn the essential methods and concepts used for creating 1D part and assembly tolerance stacks.
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