Professor Markus Buehler publishes paper in Science Advances on using spider silk for robotic muscles

March 8th, 20192019 News in Brief

McAfee Professor of Engineering and Department Head Markus Buehler, former postdoc Anna Tarakanova and Claire Hsu ’20 published a paper in Science Advances about the use of spider silk for robotics muscles. The spider silk’s robustness and ability to contract and twist above a certain level of relative humidity in the air could assist in the creation of artificial muscles for soft robotics or smart fabrics. Read more on MIT News.

McAfee Professor of Engineering and Department Head Markus Buehler, former postdoc Anna Tarakanova and Claire Hsu ’20 published a paper in Science Advances about the use of spider silk for robotics muscles. The spider silk’s robustness and ability to contract and twist above a certain level of relative humidity in the air could assist in the creation of artificial muscles for soft robotics or smart fabrics. Read more on MIT News.

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Mechanics of Materials: Mixing Concrete

March 7th, 2019Mechanics of Materials

By Rayna Higuchi '20 Hi CEE! I’m Rayna, a student in the Mechanics and Materials track, blogging about my experiences in Course 1. Today I’ll be talking about the class Mechanics of Materials (1.035), taught by Professor Ulm, with additional instructors Stephen Rudolph and Omar Al-Dajani. The purpose of the lab we ran on February 27th was to study the rheological properties of a concrete mixture. Rheology is a branch of physics that deals specifically with material flow and has been the subject of the course for the first several weeks. Given its purpose in everything from roads to bridges to skyscrapers, it is crucial that we understand how concrete moves before hardening. As a homework, we were tasked with determining the optimal proportions for a concrete mix. We thus came to class with the calculated ideal mix proportions of water, cement, sand, and gravel. These are the most basic materials of concrete. The sand and gravel, known as the aggregates, take up space in the concrete so that we don’t need as much cement, which acts as the glue holding everything together. Finding good values for each of these is important. Cement is the ingredient that requires the most energy to produce, and thus releases the most carbon dioxide. If we can minimize this, we will drastically reduce the carbon footprint of a project. However, with too little cement, the material will begin to lose strength. Determining these values is a balancing act, and will change depending on the requirements of [...]

By Rayna Higuchi ’20

Hi CEE! I’m Rayna, a student in the Mechanics and Materials track, blogging about my experiences in Course 1. Today I’ll be talking about the class Mechanics of Materials (1.035), taught by Professor Ulm, with additional instructors Stephen Rudolph and Omar Al-Dajani.

The purpose of the lab we ran on February 27th was to study the rheological properties of a concrete mixture. Rheology is a branch of physics that deals specifically with material flow and has been the subject of the course for the first several weeks. Given its purpose in everything from roads to bridges to skyscrapers, it is crucial that we understand how concrete moves before hardening.

As a homework, we were tasked with determining the optimal proportions for a concrete mix. We thus came to class with the calculated ideal mix proportions of water, cement, sand, and gravel. These are the most basic materials of concrete. The sand and gravel, known as the aggregates, take up space in the concrete so that we don’t need as much cement, which acts as the glue holding everything together. Finding good values for each of these is important. Cement is the ingredient that requires the most energy to produce, and thus releases the most carbon dioxide. If we can minimize this, we will drastically reduce the carbon footprint of a project. However, with too little cement, the material will begin to lose strength. Determining these values is a balancing act, and will change depending on the requirements of the final concrete, the aggregates used, and the type or components of the cement.

Claire Holley (’21), Rayna Higuchi (’20), Chelsea Watanabe (’21), and Luke Bastian (’21) measure components pre-mixing. Photo courtesy of Stephen Rudolph.

Much like baking a cake, we first mixed together the dry ingredients, then added water. The mixing was the fun part—once everything was wet, we could take off our dust masks and play around with the concrete. My group, self-named “Boyfriend Material,” built a snowman! Alas, Crunchy the Cementman had an even shorter lifespan than his snowy counterpart. It wasn’t long before he faded into an unrecognizable blob.

The birth of Crunchy the Cementman. Photo courtesy of Stephen Rudolph.

Following mixing, we performed a slump test. This is a common test used to determine the pumpability/workability (how easy the concrete is to pump or otherwise manipulate) of a concrete mixture. You fill up a cone 1ft high, then lift the cone straight upward. The change in height, known as the slump, can be used to gain insight as to how easily the concrete will flow. Depending on your project, you might desire lower or higher workability. A simple method to increase the workability is to increase your water ratio, but this will likely reduce the final strength of your concrete. Instead, a common method to increase pumpability without compromising the final strength of the concrete is to add something called a superplasticizer. As a liquid, the concrete will appear to be waterier, but will have similar hardened strength values as without the superplasticizer. This is useful to creating high-performance concrete.

A beautiful slump. Photo courtesy of Stephen Rudolph.

Once the slump tests were complete, we took the concrete and placed it in five molds to harden for the next three weeks, when we will test their compressive strength.

CEE you next time!

Preparing the samples for curing. The machine vibrates rapidly, helping to remove any air bubbles from the sample. Photo courtesy of Stephen Rudolph.

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Mechanics of Materials: Testing Tensile Strength

March 7th, 2019Mechanics of Materials

By Rayna Higuchi '20 Hi CEE! I’m Rayna, a student in the Mechanics and Materials track, blogging about my experiences in Course 1. Today I’ll be talking about the class Mechanics of Materials (1.035), taught by Professor Ulm, with additional instructors Stephen Rudolph and Omar Al-Dajani. The purpose of the lab we ran on March 5 was to study the elastic behavior of materials when subjected to a tensile (pulling) force. To do this, we took dogbone specimens, depicted below, of different alloy types. Before testing, we measured the width and length of the dogbone. We then screwed it into a hydraulic machine, capable of exerting a force of 22,000 pounds! For reference, I am 135 pounds. This machine can exert a force equivalent to me if I was stacked 163 times. If you’re familiar with the work Yertle the Turtle by Dr. Seuss, that would be a lot. Luke Bastian (’21) screws a dogbone into the hydraulic machine. Photo courtesy of Stephen Rudolph As we pulled on the specimen, it originally elastically deformed. This means that once the pressure is released, the material will return to its original shape. As we continue to pull on it, the material begins to deform permanently. Consider when you bend an eraser: up to a certain point, the eraser will return to its original shape. This is elastic deformation. However, once you bend it far enough, you deform the eraser in ways that can’t be undone. This is plastic deformation. As a class, we [...]

By Rayna Higuchi ’20

Hi CEE! I’m Rayna, a student in the Mechanics and Materials track, blogging about my experiences in Course 1. Today I’ll be talking about the class Mechanics of Materials (1.035), taught by Professor Ulm, with additional instructors Stephen Rudolph and Omar Al-Dajani.

The purpose of the lab we ran on March 5 was to study the elastic behavior of materials when subjected to a tensile (pulling) force. To do this, we took dogbone specimens, depicted below, of different alloy types. Before testing, we measured the width and length of the dogbone. We then screwed it into a hydraulic machine, capable of exerting a force of 22,000 pounds! For reference, I am 135 pounds. This machine can exert a force equivalent to me if I was stacked 163 times. If you’re familiar with the work Yertle the Turtle by Dr. Seuss, that would be a lot.

Luke Bastian (’21) screws a dogbone into the hydraulic machine. Photo courtesy of Stephen Rudolph

As we pulled on the specimen, it originally elastically deformed. This means that once the pressure is released, the material will return to its original shape. As we continue to pull on it, the material begins to deform permanently. Consider when you bend an eraser: up to a certain point, the eraser will return to its original shape. This is elastic deformation. However, once you bend it far enough, you deform the eraser in ways that can’t be undone. This is plastic deformation. As a class, we tested ductile (stretchy) and brittle (crunchy) materials. We expect the brittle materials to break suddenly, and with little warning, while the ductile materials will slowly deform before breaking completely.

The dogbones post-testing. If you look closely, for most of them there is a noticeable thinning around the point of fracture. However, the more brittle pieces lack this characteristic. For example, the middle piece labeled “Luke f140 steel quenched test 6”, there is little change in the diameter near the break. Photo courtesy of Stephen Rudolph.

We then remeasured the dogbone to see the change in diameter at the point of failure as well as the change in length. The loading graphs were stored by the machine and will help us find the material properties of the various alloys. As one might infer from the class name, this semester we hope to learn about the mechanical properties of materials. Within this category falls the material’s ability to support tensile load. Metals, specifically steel, are often used in tension. Bridge cables and rebar are examples that come immediately to mind.

This lab was super fun to do! In the past, I have mostly been working with cement and compressive loads. It was interesting to switch things up in both these regards, working with metals (ooh!) and tension (ahh!). When the dogbones broke they would make loud noises. Like dogs and small children, I find this exciting.

CEE you next time!

Dogbone post-break, still in the hydraulic machine. The black object extending to the right is used to measure the change in length while the material is elastically deforming. Photo by Rayna Higuchi.

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PhD student Josh Moss highlighted for his research on urban pollution

March 4th, 20192019 News in Brief

PhD student Josh Moss studying Atmospheric chemistry in Professor Jesse Kroll’s Lab, is examining the chemistry of gases and particles in the atmosphere that humans are releasing, and their interactions with existing particles in the atmosphere. Moss utilizes computer modeling in conjunction with the controlled atmospheric chamber in the lab to investigate the gas phase reactions originating from smog particles. Read more on MIT News.  

PhD student Josh Moss studying Atmospheric chemistry in Professor Jesse Kroll’s Lab, is examining the chemistry of gases and particles in the atmosphere that humans are releasing, and their interactions with existing particles in the atmosphere. Moss utilizes computer modeling in conjunction with the controlled atmospheric chamber in the lab to investigate the gas phase reactions originating from smog particles. Read more on MIT News.

 

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CEE receives top rankings in civil and structural engineering and environmental science from QS World University Rankings

March 4th, 20192019 News in Brief

The 2019 QS World University Rankings announced that CEE is ranked first in civil and structural engineering and second in environmental science. The rankings are based on research quality and accomplishments, academic reputation and graduate employment. Read more on MIT News.

The 2019 QS World University Rankings announced that CEE is ranked first in civil and structural engineering and second in environmental science. The rankings are based on research quality and accomplishments, academic reputation and graduate employment. Read more on MIT News.

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Professor Markus Buehler and the Laboratory for Atomistic and Molecular Mechanics publishes paper on paraffin-enabled graphene transfer

March 2nd, 20192019 News in Brief

McAfee Professor of Engineering and Department Head Markus Buehler, research scientist Francisco Martín-Martínez, and research affiliate Jingjie Yeo from the Laboratory for Atomistic and Molecular Mechanics (LAMM) published a paper in Nature Communications on paraffin-enabled graphene transfer. The findings open the doors to high-performance electronics based on large-area two-dimensional materials. Read more here.  

McAfee Professor of Engineering and Department Head Markus Buehler, research scientist Francisco Martín-Martínez, and research affiliate Jingjie Yeo from the Laboratory for Atomistic and Molecular Mechanics (LAMM) published a paper in Nature Communications on paraffin-enabled graphene transfer. The findings open the doors to high-performance electronics based on large-area two-dimensional materials. Read more here.

 

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