1. Aquatic
In June 2023, OceanGate’s Titan submersible tragically imploded during a deep-sea expedition. The failure occurred about 1 hour and 45 minutes into the dive at a depth of nearly 3,800 meters, where immense pressure exceeded the structural limits of the sub’s carbon fiber–titanium composite hull. Subsequent investigations revealed that the vessel had not undergone standard certification procedures and that repeated warnings from experts about material fatigue and design safety were ignored. The disaster highlighted critical engineering flaws, particularly the use of carbon fiber for deep-ocean applications, and raised global concerns over the lack of regulation and safety oversight in private deep-sea exploration.
2. Terrestrial
A volcanic eruption releases basaltic lava, which spreads out in a thick, relatively uniform lava flow. As the lava cools, it contracts. Cooling begins from the top and bottom surfaces (in contact with air or ground) and moves inward. During cooling, the lava shrinks. Because basalt is brittle, this shrinkage causes tensile stresses to build up, leading to cracks. The cracks propagate downward and form a hexagonal (or polygonal) pattern, which is the most efficient way to relieve stress. This pattern extends vertically through the flow, creating the long, regular columns.
A dolmen, an ancient architectural structure, typically comprises two or more upright megaliths supporting a large, flat horizontal capstone. These structures have been found across the world, yet their origins—when, why, and by whom the earliest dolmens were constructed—remain unclear. The oldest known artifacts of this type, dating back approximately 7,000 years ago, are discovered in Western Europe. It's remarkable how our ancestors crafted these structures to achieve equilibrium, making them a perfect example in statics and fundamental mechanics.
My family went snow skiing and stayed in a log cabin. The walls were constructed from logs and chinking materials (e.g., mortar, clay, and sand mixtures). I noticed cracks in the chinking between the logs, which immediately reminded me of transverse cracks in polymer-fiber composites at the microscopic level. The logs essentially represent the fibers, while the chinking material acts as the matrix, illustrating a similar transverse cracking phenomenon at the macroscopic scale. The space between those cracks also make sense as observed in polymer-fiber composites.
Hydraulic fracturing or fracking is a well-stimulation process in which a pressurized fluid is pumped into low-permeability rock to create small fractures, increasing pathways for oil or gas to flow to the well. It can trigger seismicity because the injected fluid raises pore pressure and changes local stresses, which reduces frictional resistance on nearby pre-existing faults. Most of the time these events are micro-seismic, but felt earthquakes can occur if a critically stressed fault is close enough and becomes hydraulically connected to the injected zone.
If you have much experience for the fracture behavior of different structures, such as adhesively-bonded joints, fiber-reinforced polymers, and others. You probably can tell immediately that this ice load was under global shear (Mode II), and the fracture pattern with discontinuous, inclined cracks was caused by local maximum principal stress (Mode I).
People may ask why ice, which is considered brittle, fractured in this manner. Should it fracture differently than, for example, the fiber-reinforced polymer composites I mentioned earlier? If you are familiar with quasi-brittle fracture mechanics, you will know that ice is also a quasi-brittle material, like polymer composites.
3. Aerial
When supercooled water droplets in clouds impact cold aircraft surfaces, they freeze into layers of ice. This leads to weight gain, reduced lift, and potential loss of control. Research on anti-icing techniques (to prevent ice formation) together with de-icing methods (to remove ice once formed) is therefore essential for improving flight safety and operational reliability.
Thermal barrier coatings are advanced material systems designed to protect components exposed to extreme temperatures, such as turbine blades, exhaust systems, and combustion chambers. Typically composed of a ceramic topcoat such as yttria-stabilized zirconia and a metallic bond coat. TBCs can enhance fuel efficiency, reduce oxidation and corrosion, and support lightweight material integration in aerospace, automotive, and energy applications. One issue is thermal cycling durability, where repeated heating and cooling cause microcracking, delamination, or spallation due to thermal expansion mismatch between coating layers and the substrate. (Credit: Progressive Surface)
4. Celestial
This is what happens to aluminum when hit by a 1/2 oz (14g) piece of plastic going 15,000 mph (24,000 km/h) in space.
Moon dust is part of the lunar regolith, the dusty and rocky material that covers much of the Moon’s surface. It poses significant challenges for astronautics and space structures. For example, the fine gray powder adhered to spacesuit fabrics and entered the capsule, causing irritation to the eyes, nose, and throat. (Credit: NASA)
5. Biotic
The integration of hard and soft materials presents persistent challenges, often resulting in stress localization and eventual failure in applications such as biomedical implants, structural joints, and electronic assemblies. In biological systems, however, this problem is addressed effectively. At the tendon–bone attachment, known as the enthesis, hydrogen-bond interactions between collagen and mineral particles remain deliberately weak. This prevents the formation of a rigid, brittle network and instead promotes compliance, toughness, and long-term resilience. Here, durability is achieved not by maximizing bond strength but by using weak hydrogen bonds to regulate interfacial structure.
After skin damage such as cryotherapy experienced recently, the skin turns white or becomes blistered within a week. A scab crust forms in 1–2 weeks. Since there is no vascular or structural anchoring (i.e., a scab is not anchored by blood vessels or nerves), it can come off easily due to the lower interfacial adhesion. The reduced moisture leads to shrinkage and causes the delamination between the scab and the skin. In addition, as the epidermis regenerates from below, new skin cells grow and migrate to seal the wound. This pushes the scab upward and initiating delamination from the edge.
Ligament tears and sprains are common injuries among athletes, particularly in sports that involve sudden movements, twisting, or pivoting. One of my favorite sports is track and field, where events like the 100-meter sprint place significant stress on the joints, sometimes leading to anterior cruciate ligament (ACL) injuries in the knee or ankle. The 100-meter world record stands at 9.53 seconds, highlighting the incredible speed and intense impact forces involved. I once recorded a personal best of 11.8 seconds 18 years ago...