Author: Isaac Gendler

Shear Stress

Shear Stress

Shear Stress

02/24/17

“What happens when stress is applied parallel to the surface area of a material?”
Any force acting upon a three-dimensional object will produce an internal stress. However, how do engineers classify the types of stress that are parallel to the material’s surface area? Well, after many years of research, this phenomenon has been classified as a shear stress. A shear stress will produce a shear strain in the object proportional to the object’s modulus of rigidity, which can be symbolically represented with the equation (Tau = G*(Gamma), with (Tau) being the shear stress (Gamma) being the shear deformation and g being the modulus of rigidity. The higher a material’s shear strength is, the more it will be able to resist shear strength.

Microscope optics

Microscope optics

Microscope optics

02/23/17

“How exactly do microscopes work?”
Microscopes are one of the most important inventions that humanity has ever created. With these devices, we can view the microscopic world in unparalleled detail, enabling accurate observations for a myriad of scientific fields. However, have you ever wondered how they worked in the first place? Well, let’s use our engineering mindset to think about it. Before we begin to work on this problem, let’s see if a similar problem has been solved before. If you research hard enough, then you will probably realize that our fundamental problem, taking a small image and magnifying it to a larger one, has been solved by refracting telescopes already. Believe it or not, optical microscopes use the exact same setup as these telescopes! This shows how discoveries in one field of science can be applied to a completely different one as well, and through intercommunication can both field benefit.

Refracting telescope

Refracting telescope

Refracting telescope

02/22/17

“How do old-school telescopes work?”
Telescopes are one of the most amazing machines that humanity has constructed. Not only have they become a symbol for scientific endeavor but a cultural landmark as well. However, have you ever wonder how they worked (specifically the old-school ones)? Well, let’s use our engineering mindset to figure out this scientific device. If we were to uncover the case of these machines, we would find two convex lenses. Now, if we were to trace a ray diagram through the lenses, we would find something very interesting. First, the incoming light from the object would converge onto a real image on the opposite side of the first lens. The light from this image would then be received by the second lens, which shifts the light’s direction in such a way that their paths would converge on the receiving side of the lens, forming a magnified virtual image, therefore creating an enlarged image that the human eye can see. This form of a telescope is called a refracting telescope, and has been used since the days of Galileo!

Diffusion

Diffusion

Diffusion

02/21/17

“How do substances spread?”
Chemical substances can be found everywhere. However, these objects are almost always never in static position, and will constantly move around. So how can we classify the phenomena of the dispersion of chemicals? Well, after many years of research, Chemists have developed the concept of diffusion. Diffusion is when molecules from a high concentration (dense collection) diffuse into the surrounding environment until an equilibrium state is reached. Diffusion not only happens in fluids but can also occur in solids. Specifically, the atoms in solids are always vibrating, and if there are holes within the lattice, then atoms from neighboring gasses can enter the substance and effect its material properties. An example of this can be seen with piping. If the material of the pipes is not properly designed, then atoms of the transport fluid can merge with the solid material and cause brittleness which will eventually lead to breakdown.

Polycrystals

Polycrystals

Polycrystals

02/20/17

“How do we classify crystals that have their periodicity disrupted?”
One of the most fundamental properties of crystals is their periodic structure. However, because of the sheer complexity of the physical universe, a perfect specimen is very rare to obtain. Specifically, the smooth periodicity is often disrupted, and the molecules of crystals will be forced into different grains going in different directions. Because these objects are so common, materials scientists and engineers have decided to term these crystals polycrystals. This interlocking nature makes polycrystals stronger than their monocrystalline counterparts as well as more heat resistant.

Crystals

Crystals

Crystals

02/19/17

“What is a crystal?”
No other material has captivated the imagination of humanity more than crystals. These otherworldly structures have been used for all forms of practices, ranging from pagan rituals to pseudoscientific medical therapies. However, as scientific thinkers, we must not be satisfied with primordial definitions and must analyze what these objects are in their true nature. If one were to shrink down to the size of a molecule and explore the inner fabric of a crystal, then they would find an entire world of atoms fashioned in patterned arrangements. And this is exactly what constitutes a crystal, a solid with a patterned arrangement of atoms! Crystals tend to form when liquids cool and harden, since when the atoms cool they tend to gather together in an ordered manner to form a crystal lattice. Crystals have no “special magical powers” and are as bounded to the laws of nature and you and me.

Crystal defects

Crystal defects

Crystal defects

02/18/17

“How do we classify imperfections in crystals?”

 

Ideal crystals never exist. For every material arrangement out there, there exists some form of a defect within its structure. Specifically, there will be some form of irregularity through its patterned nature called a crystal defect.These defects can be classified into three distinct types: Point defects (when a single atom in the crystalline lattice is placed out of order), Linear defects (when atom groups are found to be erroneous), and planar defects (two-dimensional errors which include grain boundaries and other mishaps that occur between boundaries in a material). The word defect is actually a misnomer since these phenomena can actually strengthen the properties of a material

Grain boundaries

Grain boundaries

Grain boundaries

02/17/17

“What happens when multiple grains in a crystal collide?”
Polycrystalline materials have grains that flow in numerous different directions. However, to make a continuous object, these grains must coalesce with one another. So what exactly happens at this grain boundary? Well, believe it or not, these grain boundaries actually cause the strength of the material to increase! The reasoning for this is that fragmentation along a material occurs across a row in a crystalline grain, so anything that limits this row will act as a dampener to the system.

Crystal grain

Crystal grain

Crystal grain

02/16/17

“How do we describe when crystals have arrangements in different directions?”
Crystals are fantastic structures, with millions of different molecules being chained together in a uniform pattern. However, sometimes these chains will be in different directions from one another. Because these patterns are so prevalent, Materials scientists and engineers have decided to term this feature in crystals a grain. Grains are a very important property in materials and can have a large influence on the macroscopic behavior of a material