#mechanical stress

[whats-in-a-sentence]

Plant signal transduction mechanisms may be relatively rapid or extremely slow (Figure 15.1)

"Plant Physiology and Development" int'l 6e - Taiz, L., Zeiger, E., Møller, I.M., Murphy, A.

[materialsscienceandengineering]

'Twist and shine': Development of a new photoluminescent sensor material

Stress sensors are important tools when it comes to evaluating the robustness of a material facing strong mechanical forces. OIST researchers have just published in Advanced Materials an article reporting a new kind of sensor molecules that brightens up when the material they are incorporated into comes under heavy mechanical stress.

Such light-based sensing molecules, also called photoluminescent mechanophores, are not new, but currently available applications are single-use only. They would typically involve a strong force—compressing, twisting or stretching for example—breaking a specific chemical bond between two atoms or irreversibly pulling apart two molecular patterns in the sensing molecule, changing the wavelength - and thus the color - of the light emitted by the mechanophore. Once these molecules have radically changed their structure in response to this force, it is extremely difficult to return to the initial situation. While these mechanophores are useful to understand the mechanical properties of an item or a material, they do not suit well for repeated exposure to mechanical stress.

To overcome this issue, Dr. Georgy Filonenko and Prof. Julia Khusnutdinova from the Coordination Chemistry and Catalysis Unit designed a photoluminescent mechanophore that retains its properties over time and under repeated incidences of mechanical stress. The researchers incorporated the stress-sensing molecule into a common polymer material called polyurethane, widely used for everyday items from mattresses and cushions to inflatable boats, car interiors, woodworking glue and even spandex.

Read more.

[materialsscienceandengineering]

Single-angle ptychography allows 3-D imaging of stressed materials

Everyone reacts differently under stress—even the relatively orderly atoms in a crystal. If scientists could get a clear picture of how planes of atoms shift and squeeze under stress, they could make use of those properties to provide emerging technologies, like nanoelectronics and next-generation semiconductor components, with extra speed or functionalities. However, creating this picture requires new techniques for imaging atoms in materials and their behavior in different environments.

In a recent collaborative study from the Institut Fresnel, IBM and the U.S. Department of Energy's (DOE) Argonne National Laboratory, scientists developed a new form of imaging that uses X-ray diffraction patterns, called single-angle Bragg ptychography.

Although Bragg ptychography and especially X-ray diffraction have been around for a while, single-angle Bragg ptychography allows for easier reconstruction of 3-D data about how strain affects a material.

In X-ray diffraction, the atoms within a material "scatter" the incoming X-rays, producing a signal on a detector. Because there are so many overlapping diffraction events happening simultaneously, it can be hard to identify the contribution of a particular small region of the lattice to the overall signal. To compensate for this, scientists use a method called Fourier analysis, which essentially converts the overall signal to a series of waves with peaks and valleys that correspond to the relative intensities of various parts of the signal.

Read more.

[materialsscienceandengineering]

Novel laminated nanostructure gives steel bone-like resistance to fracturing under repeated stress

Metal fatigue can lead to abrupt and sometimes catastrophic failures in parts that undergo repeated loading, or stress. It's a major cause of failure in structural components of everything from aircraft and spacecraft to bridges and powerplants. As a result, such structures are typically built with wide safety margins that add to costs.

Now, a team of researchers at MIT and in Japan and Germany has found a way to greatly reduce the effects of fatigue by incorporating a laminated nanostructure into the steel. The layered structuring gives the steel a kind of bone-like resilience, allowing it to deform without allowing the spread of microcracks that can lead to fatigue failure.

The findings are described in a paper in the journal Science by C. Cem Tasan, the Thomas B. King Career Development Professor of Metallurgy at MIT; Meimei Wang, a postdoc in his group; and six others at Kyushu University in Japan and the Max Planck Institute in Germany.

"Loads on structural components tend to be cyclic," Tasan says. For example, an airplane goes through repeated pressurization changes during every flight, and components of many devices repeatedly expand and contract due to heating and cooling cycles. While such effects typically are far below the kinds of loads that would cause metals to change shape permanently or fail immediately, they can cause the formation of microcracks, which over repeated cycles of stress spread a bit further and wider, ultimately creating enough of a weak area that the whole piece can fracture suddenly.

Read more.

[beele]

Marine Sealing Solutions

The SLIPSIL sealing plug is the ideal solution for the fire safe and gas and water tight sealing of transits carrying single or multiple plastic or metal pipes.

Installing SLIPSIL is extremely simple and does not require any bolting or other mechanical outfitting. The plugs can already be exposed to high pressures immediately after installation.

SLIPSIL plugs cause no mechanical stress and avoid corrosion problems. That offers owners of ships or buildings the possibility to save on maintenance costs.

The service life of the SLIPSIL plugs easily exceeds 20 years under normal environmental conditions. The plugs can be used in a very wide temperature range. Even at low temperatures down to -50° C the rubber stays flexible and does not harden excessively as other rubber types will do.

[biology-geology-beaches-india]

The Scientific Research Notes Of S. Sunkavally (years: 2002-2011).

1747-1748.

[quirksphere]

Minimize Electrical Stress with Star Delta Starters Star delta starters are essential for starting large motors smoothly, minimizing electrical and mechanical stress. Discover their benefits and how they can improve your operations. Star delta starters help in reducing the starting current and preventing electrical and mechanical shocks to the system, ensuring a longer lifespan for your motors.

[quirksphere]

Extend Motor Lifespan with Soft Starters

Reduce mechanical stress and prolong the life of your motors with soft starters. Understand their role in smooth motor startups and how they protect your equipment from damage. Soft starters are essential for reducing the inrush current, providing a gradual ramp-up of motor speed, which minimizes wear and tear.