What is metal fatigue

What is metal deformation and metal fatigue? 2020

All metals deform (stretch or compress) when they are stressed, to a greater or lesser extent. This deformation is a visible sign of metal deformation.

In metallurgy, warp can be defined as the deformation of metal due to stress. In other words, it is a measure of how much the metal has been stretched or compressed compared to its original length. If there is an increase in the length of a piece of metal due to stress, it is called tensile strain.

But if there is a reduction in length, it is a compressive deformation.

Metal strain in malleable (bending) materials

Some metals (such as stainless steel and many other alloys) cause stress. This allows them to bend or deform without breaking. Other metals, such as cast iron, fracture and disintegrate quickly under stress. However, even stainless steel will finally weaken and break when subjected to enough stress.

Metals such as mild steel bend rather than break under stress. However, at a certain level of stress, they reach the well-understood “harvest point.” One of them reaches the yield point, the metal becomes “stressed”.

This means that more stress is required to deform the metal. The metal becomes less ductile or flexible. In some ways this makes the metal harder. But while strain hardening makes it harder for the metal to deform, it also makes the metal more brittle.

Brittle metal can break or fall through quite easily.

Metal strain in brittle materials

Some metals are brittle, meaning they are especially susceptible to breaking. Brittle metals include medium-purity and high-carbon steels. Unlike malleable materials, these metals do not have a clearly defined yield point. Instead, when they reach a certain level of stress, they break down.

Brittle metals are very similar to other brittle materials such as glass, stone and concrete. Like these materials, they are strong in certain ways, but because they cannot bend or stretch, they are not suitable for certain purposes.

Measuring metal strain

The most common measure of deformation in metals is called engineering stress. Engineering stress can be calculated as the change in length divided by the original length. For example, a 2-inch titanium rod stretched to 2.2 inches is said to experience a tensile stress of 0.1 or 10 percent.

Metal fatigue arising from metal strain

When ductile metals are stressed, they deform. If the stress is removed before the metal's yield strength is reached, the metal returns to its original shape. While the metal appears to have returned to its original state, there are actually tiny imperfections at the molecular level.

Every time a metal is deformed and then returns to its original shape, large molecular fractures occur. After many deformations, there are so many molecular fractures that the metal cracks. When this happens, it is described as "metal fatigue." Metal fatigue is irreversible.

Metal fatigue is especially problematic in situations where metal is stressed over and over again.

For example, it was a major cause of aircraft failure before it was fully understood. To avoid metal fatigue, it is important to regularly examine live metal samples using a microscope.

Source: https://ru.routestofinance.com/what-are-metal-strain-and-metal-fatigue

Articles -

AS Pavel Solomkin, head of the body station at Major Auto, SAYS, slight metal fatigue usually manifests itself in creaking interior parts or leaking door seals. Such symptoms are unpleasant, but not yet critical.

But a more noticeable decrease in body rigidity can lead to a deterioration in the vehicle’s handling and stability. In particular, sometimes it is not possible to adjust the wheel alignment - the aged metal simply ceases to support the load.

Therefore, after some time after adjustment, the wheel alignment angles go beyond the permitted limits.

In the most “neglected” cases, cracks form on the body due to excessive loads (often this defect appears in the area of ​​the front suspension strut supports). If they are not detected in time, then over time the car owner risks getting into an accident. For example, when on the next pit the tired metal of the bracket of some suspension arm cannot withstand it and breaks. After all, in this case the car will become uncontrollable.

In addition, a weakened body cannot effectively absorb impact energy, and occupant protection may be insufficient in the event of an accident. And among other things, a car with a “tired” body is difficult to maintain. For example, according to servicemen, it happened that when lifting a car on a lift, its side windows burst and the windshield cracked. The body was losing its former rigidity to such an extent. With a decrepit car, this can also happen on the road, say, when passing speed bumps.

Why is the body weakening?

THIS HAPPENS for many reasons. The most common is increased load on the car. For example, when towing a trailer. It is used not only by avid summer residents, but also by lovers of active recreation. They carry platforms with all-terrain vehicles, motorcycles, jetskis, boats and yachts. Therefore, the likelihood of finding a former towing vehicle on the secondary market is quite high.

In such cars, shocks and blows from the coupling device are constantly transmitted to the body, since even an experienced driver is not always able to smoothly start and brake with a heavy load behind. Moreover, the towbar is usually attached to the power elements of the body. That's why they suffer in the first place.

The use of seemingly harmless additional luggage racks also does not benefit the car. It doesn't matter what type they are - roof mounted or station wagon rear door mounted. In any case, the atypical load gradually weakens the body. Traveling with the trunk door open can also damage your car.

After all, many owners of station wagons, hatchbacks and minivans use them to transport small loads, among which there are often long items that do not fit into the cabin. So you have to put the “tail” of your luggage out the barely closed door.

If you drive this often, it significantly reduces body rigidity.

Sometimes this happens due to the folded rear sofa, which on some cars plays the role of a power strut for the body. If you remove it, and besides, load the trunk too much, then the rear of the car will undergo serious deformations.

The bodies of cars that have once been in serious accidents are not in the best shape. Because after straightening and stretching, the metal loses its original properties.

There is a misconception that SUV bodies are stronger than those of conventional passenger cars. This is not entirely true. After all, even real all-terrain vehicles like the Land Rover Defender or Jeep Wrangler sometimes show signs of fatigue. Such machines are initially designed for use in harsh conditions, and their power structure is based on a durable frame. But with frequent trips to serious off-road conditions, it becomes noticeably deformed, and because of this, the body suffers to one degree or another.

Even if you buy a car from an exemplary owner who took care of it, cared for it and cherished it, there is still a risk of getting a “tired” copy. The fact is that Russian bad roads are akin to a vibration test stand, and even with careful use, after 5-7 years the first signs of metal aging appear on many cars.

And on sports models they can appear even earlier. After all, the rigid suspension of such cars transfers most of the shocks and impacts to the body.

Examination

BEFORE purchasing, ask the seller in detail about the mode in which the car was used. Of course, not every owner will tell you all the details, but you can learn something from the appearance of the car. For example, a hitch is usually attached not for the sake of beauty, but for towing a trailer. Characteristic marks on the roof will indicate that there was an additional trunk here. This means that such a specimen must be examined with special care.

The same applies to jeeps with large custom wheels and increased ground clearance. As a rule, this is the first stage of preparation for off-road raids. It is unlikely that the owner of such an all-terrain vehicle used it only for driving on asphalt.

Inspect the trunk. Worn, dirty, torn upholstery or, worse, construction debris on the floor - all these are, with a high degree of probability, signs that the car was used as a truck.

Try all the doors in action. They should open and close with the same sound and force. Make sure that when open, the doors do not sag and the trunk lid does not dangle in the opening. If there is a sunroof built into the roof of the car, check that too. In a tired body, it sometimes gets stuck in the guides.

For a test drive, park at the curb with one wheel on the curb. It happens that in this position it becomes difficult to open a door without using a special tool. This means that the metal has already seriously aged.

Inspect the tires - uneven wear will indicate improper alignment. Perhaps the cause of this problem was excessive body fatigue.

Finally, find out whether the car you like has been in serious accidents when the power elements of the body suffered. As mentioned above, even after high-quality repair of such damage, the strength of the “skeleton” of the car is noticeably reduced. Therefore, if the seller does not have supporting documents that the car was restored in a specialized workshop, there is a reason to refuse the purchase.

Keep in mind: even a professional can sometimes find it difficult to take into account all these nuances. Therefore, if you do not have complete confidence in your own abilities, we advise you to take your car to a branded body shop, where they have the equipment necessary for such a check.

Source: http://www.MotorPage.ru/infocenter/autoarticles/Stal_tozhe_ustaet.html

What things in the house are sources of fatigue?

Of course, some things in the house make our life much easier. But there are also those that contribute to worsening mood and fatigue. Rambler found out what was wrong with the objects around us in the house.

Favorite TV

In the modern world, we are faced with an endless stream of information. Every day they try to tell us some news. But watching TV shows, news programs, serials and scandalous TV shows for a long time takes a lot of time. And this is far from the only reason that requires reducing TV viewing.

The dim light of the TV screen also has a negative impact. Dim light in the evening provokes fatigue, blues, and even such a serious illness as depression. As for electromagnetic radiation, the human immune and endocrine systems suffer from its effects.

The body’s defenses against dangerous infections weaken, fewer happiness hormones are produced, which worsens the general condition and mood.

Electronics in the bedroom

Statistics show that about 37% of people prefer to scroll through news on social networks, play games on the phone, or bury themselves in an e-book before going to bed.

But few people remember that bright light emanating from gadgets leads to eye irritation, disruption of the ear nerve and poor blood circulation in the brain. This is why our body cannot relax properly and the time to fall asleep is delayed.

In the morning, a person gets up gloomy and overwhelmed, since his body does not have time to rest at all.

Uncleaned apartment

Despite the fact that all people have different attitudes towards clutter in the apartment, everyone, without exception, is more comfortable in a clean and tidy apartment. Only for some, cleaning is a boring and difficult task, while for others it is a way to please themselves and their loved ones.

“Cleaning can distract you from negative thoughts. Keep you busy if you start to get bored. This is a certain way of meditation. Think about how you feel when you come home from work late at night and your house is dirty. Naturally, you will be irritated and angry with yourself,” explains Svetlana Gordeeva, psychologist.

Low room temperature

Scientists from the University of California have proven that for a favorable existence a person needs a moderate ambient temperature.

The body spends too much energy fighting the cold, which causes mental discomfort and a decrease in performance. A person gets tired quickly.

If the air temperature in the apartment is below 17 C°, then the respiratory organs are unable to resist acute respiratory diseases. A runny nose, cough, headaches and other symptoms may appear that do not cause positive emotions at all.

Synthetic fabrics

Fabrics made from natural materials are more suitable for a good night's rest than those made from synthetics. Artificial fabrics accumulate static electricity, which does not have a very beneficial effect on the skin and hair.

You've most likely heard the phrase "the body doesn't breathe." It is because of such tissues that our body cannot correctly determine the ambient temperature and “ventilate”. As a result, the person suffers from insomnia.

And lack of sleep leads to you feeling sleepy and lethargic throughout the day.

Lack of warm colors in the interior

Apartment renovations can be another factor affecting your emotional state. To avoid getting depressed, it is better to stick to warm colors when choosing an interior design. Then they will fill the room with radiance, create a feeling of closeness to nature and calm you down. We advise you to refrain from using cold and gray shades. If you spend a long time in such a “cool” environment, you can feel boredom, melancholy, weakness and loss of strength.

Source: https://weekend.rambler.ru/items/43488547-kakie-veschi-v-dome-yavlyayutsya-istochnikami-ustalosti/

Your constant fatigue starts in your gut!

What is chronic fatigue syndrome? It can be quite a debilitating disease, forcing its owners to live with constant, persistent fatigue, regardless of the type of therapy. In addition to persistent fatigue, CFS sufferers exhibit symptoms throughout the body that are caused by an inflammatory response.

What is chronic fatigue syndrome (CFS)? It can be quite a debilitating illness, forcing its owners to live with constant, persistent fatigue, regardless of the type of therapy. In addition to persistent fatigue, CFS sufferers exhibit symptoms throughout the body that are caused by an inflammatory response.

Chronic fatigue syndrome and intestinal problems

There are a number of opinions about the origin of CFS - dysfunction in the central nervous system, metabolic imbalance, infectious inflammation, problems in the body's immune defense.

Unfortunately, today medicine does not have laboratory tests to identify this syndrome. It follows that the diagnosis is made by excluding other diseases that have similar symptoms. Additionally, there are no specific therapies or medications for CFS.

Subscribe to our INSTAGRAM account!

In the past, many doctors explained this condition as psychological dysfunction. But a recent study conducted by specialists from Cornell University identified biomarkers of this disease in the form of microbes present in the blood and intestines of humans. The dynamics of the number and activity of these microorganisms was studied. In parallel, changes were observed in brain tissue, which allowed us to draw a primary conclusion about the connection between bacteria and our brain.

What is CFS?

Manifestations of CFS are a large list of painful conditions, varying from person to person. A typical symptom is a persistent feeling of fatigue, which intensifies as physical/mental energy is expended. However, recovery takes a long time.  

In addition to classic fatigue, CFS mimics the symptoms of other diseases:

• Muscle pain
• Memory loss
• Headache
• Sore throat
• Poor night's sleep
• Enlarged lymph nodes
• Muscle twitching
• Poor, short attention span
•  Increased sweating
• Strong heartbeat
• Fainting
• Symptoms characteristic of influenza
• Poor alcohol tolerance
• Irritable bowel
• Sudden mood swings
• Fluctuations in body temperature
• Allergies to a number of foods
• Stomach and intestinal dysfunctions
• Sensitivity to light and noise

The prolonged course of CFS in the absence of proper therapy entails complications, expressed in depressive states and disruption of social life.

The conclusions of specialists from the University of California indicate that this disease often strikes people who are far from lazy, who were previously active and did hard work.

Possible causes of fatigue unexpectedly discovered in the intestines

In a special study by Cornell University specialists, the blood and excrement of 48 people diagnosed with chronic fatigue were examined and the results were compared with the analyzes of 39 healthy individuals.

The discovery may explain the “blurred” symptoms of CFS and, perhaps, lead to the development of successful therapies.

The differences between healthy volunteers and those with CFS included excrement and blood.
Experts have identified a deficiency in the diversity of intestinal microflora in CFS patients and markers of inflammation in the blood. These changes do not allow them to be clearly identified as a cause or a consequence of CFS; however, scientists were encouraged by the very presence of these markers in 83% of analyses.

Follow Econet on Pinterest!

It turns out that in the intestines of people with CFS, the state of the bacterial microflora is abnormal, and this provokes gastrointestinal and inflammatory symptoms. This fact argues against the theory of the psychological origin of CFS.  

The key to the disease may be leaky gut

The inflammatory markers found in the blood (discussed above) may be a consequence of “leaky gut”, which allows bacteria to enter the blood.”

In leaky gut syndrome, certain toxic compounds and bacteria slip through the intestinal walls into the blood. This occurs due to the formation of “gaps” between the intestinal cell membranes.

There is a connection between the dynamics of the holes and the food entering the body. I would like to focus on grain crops. Gluten stimulates a number of proteins in the intestines, which provoke the opening of intercellular junctions in the intestinal mucosa.

And the penetration of substances from the intestines into the blood provokes inflammatory and autoimmune reactions.

It is worth saying that healing and thickening the intestines reduces the inflammatory response, which can demonstrate a reduction in CFS symptoms.  

Brain changes in CFS

In 2014, experts at Stanford University identified the dynamics of the white matter of the brain in people diagnosed with CFS. Technical innovations in imaging studies have made it possible to see differences in the brains of healthy individuals and patients with CFS.

These differences are manifested by a decrease in the volume of white matter and changes in the right hemisphere. Therefore, individuals with CFS often demonstrate confusion and the development of hypochondria.  

Subscribe to our Yandex Zen channel!

The above study provides 3 conclusions. 

• Conclusion No. 1 confirmed the effect of the inflammation process on the white matter of the brain (a decrease in white matter in the brain leads to problems in transporting information).
• Conclusion #2 states that the level of abnormalities in the brain is associated with the severity of CFS symptoms.  
• Finding #3 suggests gray matter thickening in the white matter between the temporal and frontal lobes.

Fighting CFS with home remedies

All of the above allows us to think that the optimal method in the fight against CFS may be attention to the functioning of the gastrointestinal tract. A special diet can help restore the integrity of the intestinal walls and minimize the aggressiveness of harmful microflora.

• Products containing gluten and wheat flour should be removed from the diet.  
• Reduce the amount of carbohydrates you consume. Carbohydrates create an imbalance in microflora and act as food for “bad” bacteria.  
• Fiber, on the contrary, feeds bacteria that protect the intestinal walls. 
• Increase the fiber content in your diet. Fiber strengthens the intestinal walls and will help increase the number of beneficial bacteria.  
• Consume fermented foods, which are a source of natural probiotics from lactic acid bacteria.  
• Minimize the consumption of milk and dairy products. They contain milk protein - casein, which activates inflammation in the intestines.
• Fighting stress. Stress “raises” the level of acidity in the stomach and impairs the digestibility of food. All this provokes leaky gut syndrome.
• Use antibiotics in exceptional situations. These medications disrupt the microflora.
• Get tested for the presence of intestinal parasites. All kinds of viruses, fungi and parasites create digestive dysfunction.*published by econet.ru.

*Ekonet.ru articles are intended for informational and educational purposes only and do not replace professional medical advice, diagnosis or treatment. Always consult your physician with any questions you may have about a medical condition.

Subscribe to our channel!

Source: https://econet.ru/articles/vasha-postoyannaya-ustalost-beret-nachalo-v-kishechnike

Symptoms of chronic fatigue syndrome - if you are always tired

As the name suggests, it is a debilitating illness: people with chronic fatigue experience an unexplained and extreme feeling of tiredness that can last for many months and often years.

Until recently, there was a common misconception, even among doctors, that the disorder was psychological or, worse, imaginary in nature. But, this was refuted by a group of experts in 2015, which defined chronic fatigue as a "serious, debilitating condition" with obvious physical symptoms.

While there is no cure for chronic fatigue, symptoms can be treated with a variety of medications and treatments, from sleeping pills and painkillers to gentle exercise and counseling.

Read on to learn more about chronic fatigue syndrome —and the signs it's time to have your fatigue checked by a doctor.

What Causes Chronic Fatigue Syndrome

The exact cause of chronic fatigue remains a mystery—and there may be several reasons for it.

Research suggests that Epstein-Barr virus infection and possibly other infections may cause some cases of the disease. Other possible causes that have been cited include immune system problems and hormonal imbalances. But, there are still no final conclusions.

Who is at risk for chronic fatigue syndrome?

Chronic fatigue affects people of both sexes and all ethnic and economic groups. In women, however, it is diagnosed four times more often than in men.

The disease can be encountered at any age, even in childhood, but it is most common among people aged 40 to 50 years. Statistics indicate that chronic fatigue affects more people than multiple sclerosis and many types of cancer.

How is chronic fatigue diagnosed?

There is no laboratory test or biomarker for chronic fatigue , and its symptoms overlap with many other diseases, making diagnosing the disorder challenging.

The fact that it is a complex disease with varying symptoms throughout the body further complicates the situation. Most doctors are not trained to look at more than eight or ten symptoms without thinking about mental disorders. They don't know what to do about it and often label it as a mental illness, which only makes the problem worse.

To diagnose the disease, a doctor must rule out other disorders that cause fatigue and identify the characteristic signs of chronic fatigue .

1. This is not the kind of fatigue you experience after a hard week at work. This is profound fatigue that causes a sharp decline in your ability to function day to day— and lasts six months or more .

   Fatigue is not caused by excessive activity (say, moving), but by activities that you could once easily perform. Even sitting in an uncomfortable position for long periods of time can cause symptoms.

   Fatigue is relentless and does not go away with rest. At least a quarter of people with chronic fatigue become housebound or bedbound at some point.

2. Post-traumatic stress disorder means that when you subject your body to more stress (physical, mental or emotional) than it can handle, your symptoms worsen. The lymph nodes may become swollen, or there may be joint pain or pain in other areas.

   To quote one patient: “When I do something that is beyond what I can do – I literally fall apart – my body is in extreme pain, it hurts to lie in bed, it hurts to think, I can’t talk – I can’t find words to talk about. I feel like my insides are at war."

   Recovery may take a full day or longer.

3. People with chronic fatigue may “sleep” for 12 hours, but when they get up, it feels like they haven’t slept at all. Most people with chronic fatigue have trouble sleeping that they didn't have before. Common complaints include insomnia and frequent awakenings.

   This is why people with chronic fatigue need to learn to conserve the energy they have. Patients who function best are those who learn to manage the energy they have. They cope better with their symptoms because they live with much less intensity.

4. Some people with chronic fatigue have “cognitive impairment.” Basically, there is a delay in the ability to process information. They can still process information, but they cannot do it quickly. They may also have lapses in their short-term memory.

   These are problems with mental processes that may also include difficulty concentrating, problem solving and planning, difficulty completing work or interacting in social situations. Problems worsen when the patient is stressed or overly tense. Unsurprisingly, they can lead to feelings of isolation and hopelessness.

5. For many people with chronic fatigue, simply standing—for example, in the shower or while washing dishes—can lead to feelings of dizziness and even fainting. When a person lies down or elevates their legs, symptoms improve but do not necessarily go away.

   This phenomenon, which doctors call “orthostatic intolerance,” is due to the effect of chronic fatigue on the autonomic nervous system, which is “the part of the nervous system that controls everything that happens automatically in our body,” including blood circulation. Chronic fatigue is known to lead to problems with blood pressure and blood flow.

6. Pain is a common symptom of chronic fatigue, but it can come in many forms, from headaches to joint and muscle pain. It also differs in intensity from one person to another.

   To quote the patient again: “My personal experience with [chronic fatigue] feels like constant flu, hangovers, and holding my breath while constantly being electrocuted (meaning pain plays at least as much of a role in my condition as fatigue).”

You have other symptoms

There are several additional complaints reported by patients with chronic fatigue, although less frequently. Problems with the gastrointestinal tract often occur. Others complain of a sore throat, enlarged lymph nodes in the neck and armpits, genitourinary problems (including gynecological problems) and sensitivity to certain medications, foods, chemicals or other irritants.

If you notice signs of chronic fatigue —especially extreme exhaustion, post-exertional malaise, and lack of recovery from sleep—talk to your doctor. If you have a disorder, the sooner you are diagnosed, the sooner you can get the treatment you need to feel better.

Source: https://sekretizdorovya.ru/blog/priznaki_khronicheskoj_ustalosti/2020-01-19-945