Anyone who has had to start from scratch to perform materials' testing knows the amount of design effort required to execute a single test. For plain-woven fabrics that can consist of composite materials with complex microstructures, the task is more difficult. Measuring multi-axial and shear, material properties, seam strength and joint strength raises the difficulty level even further. However, plain-woven fabrics are frequently used as structural materials in air-inflated structures and quick set-up temporary structures such as shelters and bridges. As a result, the Naval Undersea Warfare Center Div. Newport (NUWCDIVNPT) was very interested in verifying the mechanical properties of these materials. To accomplish this testing, NUWCDIVNPT designed and patented a multi-axis technique and developed a fixture to implement the approach. Patent #6,860,156 was issued for a combined in-plane shear and multi-axial tension or compression testing apparatus.
To perform in-plane shear and multi-axial tension or compression, the tester has four upper linkage arms and four lower linkage arms connected by pivoting sleeves. Load transfer plates secure the specimen and provide pivot mounting points for the linkages. When the vertices are under compressive or tensile forces, each linkage can rotate toward the other linkages and apply compression or tension to the specimen. The testing machine can rotate the vertices for shear testing and apply a torsional load to the specimen. The fixture enables materials testing in several modes including uniaxial tension, uniaxial compression, biaxial tension both with and without shear, biaxial compression with and without shear, and shear only.
Both the Army and the Navy have used the fixture to successfully design air-inflatable composite structures.
Science fiction author Isaac Asimov may have the best rules for effective brainstorming and creativity. His never-before-published essay, "On Creativity," recently made it to the Web pages of MIT Technology Review.
Much has been made over the potentially dangerous flammability of lithium-ion batteries after major companies like Boeing, Sony, and Tesla have grappled with well-publicized battery fires. Researchers at Stanford University may have come up with a solution to this problem with a smart sensor for lithium-ion batteries that provides a warning if the battery is about to overheat or catch fire.
In this new Design News feature, "How it Works," we’re starting off by examining the inner workings of the electronic cigarette. While e-cigarettes seemed like a gimmick just two or three years ago, they’re catching fire -- so to speak. Sales topped $1 billion last year and are set to hit $10 billion by 2017. Cigarette companies are fighting back by buying up e-cigarette manufacturers.
Advertised as the "Most Powerful Tablet Under $100," the Kindle Fire HD 6 was too tempting for the team at iFixit to pass up. Join us to find out if inexpensive means cheap, irreparable, or just down right economical. It's teardown time!
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.