Modulus of elasticity of various materials, including steel

Modulus of elasticity of steel

►Elasticity modulus of steel
►Elasticity modulus of different steel grades

►Table of strength moduli of steel grades

►Elastic modulus for metals and alloys

►Elasticity of steels

►Strength limit

When designing steel products or structural elements, the ability of the alloy to withstand multidirectional types of loads is taken into account: impact, bending, tensile, compressive. The value of the elastic modulus of steel, along with hardness and other characteristics, shows resistance to these influences.

For example, in reinforced concrete construction, longitudinal and transverse reinforcing bars are used. In the horizontal plane they are subject to tension, and in the vertical plane they are subject to pressure from the entire mass of the structure. In places where stress is concentrated: corners, technological openings, elevator shafts and flights of stairs, more reinforcement is placed. The ability of concrete to absorb water causes constant changes in compressive and tensile loads.

Let's look at another example. During wartime, many developments in the field of aviation were created. The most common causes of accidents were engine fires. Taking off from the ground, the plane enters atmospheric layers with rarefied air and its body expands; the reverse process occurs during landing. In addition, the structure is affected by the resistance of air flows, the pressure of curved layers of air and other forces. Despite their strength, the alloys existing at that time were not always suitable for the manufacture of critical parts; this mainly led to ruptures of fuel tanks.

In various types of industry, parts of moving mechanisms are made from steel: springs, leaf springs. The grades used for such purposes are not prone to cracking under constantly changing loads.

Tensile strength

Solids are capable of withstanding limited loads; exceeding the limit leads to destruction of the metal structure, the formation of noticeable chips or microcracks. The occurrence of defects is associated with a decrease in performance properties or complete destruction. The strength of alloys and finished products is checked on test benches. The standards provide for a number of tests:

• Prolonged use of deforming force;
• Short-term and long-term shock impacts;
• Tension and compression;
• Hydraulic pressure, etc.

In complex mechanisms and systems, the failure of one element automatically causes increased loads on others. As a rule, destruction begins in those areas where stress is maximum. The safety margin serves as a guarantee of equipment safety in emergency situations and extends its service life.

Modulus of elasticity of steel

The elasticity of solids is the ability to return to its original shape after the cessation of deforming influences. For example, a block of plasticine has zero springiness, while rubber products can be compressed and stretched. When various forces are applied to objects and materials, they become deformed. Depending on the physical properties of the body or substance, two types of deformation are distinguished:

• Elastic - the consequences disappear after the action of external forces ends;
• Plastic - irreversible change in shape.

The modulus of elasticity is the name of several physical quantities that characterize the tendency of a solid body to deform elastically.

The concept was first introduced by Thomas Young. The scientist suspended weights from metal rods and observed their elongation. Some samples doubled in length, while others were torn during the experiment.

Today the definition combines a number of properties of physical bodies:

Young's modulus: Calculated by the formula E= σ/ε, where σ is the stress equal to the force divided by the area of ​​its application, and ε is the elastic deformation, equivalent to the ratio of the elongation of the sample from the beginning of deformation to the compression after its cessation.

Shear modulus (G or μ): the ability to resist deformation while maintaining volume when the direction of loads is tangential. For example, when hitting the head of a nail, if it was not made at a right angle, the product becomes distorted. In sopromat, the value is used to calculate shifts and torsion.

Bulk modulus or bulk modulus (K): changes caused by the action of a confining stress, such as hydrostatic pressure.

Punch ratio (Ⅴ or μ): the ratio of transverse compression to longitudinal elongation, calculated for material samples. For absolutely fragile substances it is zero.

Lamé's constant: the energy that provokes a return to its original form is calculated through the construction of scalar combinations.

The modulus of elasticity of steel is correlated with a number of other physical quantities. For example, when conducting a tensile experiment, it is important to take into account the tensile strength, exceeding which results in destruction of the part.

• Ratio of rigidity and ductility;
• Impact strength;
• Yield strength;
• Relative compression and tension (longitudinal and transverse);
• Strength limits under shock, dynamic and other loads.

The use of a number of approaches is determined by the requirements for the mechanical properties of materials in various industries, construction, and instrument making.

7.5. Strength of materials

Young's modulus (modulus of elasticity of the first kind) E, MPa, N/mm 2 - elastic constant in Hooke's law within the limits when deformation is proportional to stress.
Young's modulus is numerically equal to the stress that doubles the length of the sample: for steel, Est = (2.0-2.2)×10 5 MPa; for cast iron, Ech = 1.2×10 5 MPa; for copper, Em = 1.0×10 5 MPa; for aluminum, Eal = 0.6×10 5 MPa; for a rope, Ek = (1.1-1.7)×10 5 MPa: rope with an organic core, Eo = (1.1-1.3)×10 5 MPa; rope with a metal core, Emet = 1.4 × 10 5 MPa; closed rope, Ez = 1.7 × 10 5 MPa.

Hooke's law : the resulting elongation of the sample Δl under the action of an external force P is proportional to the magnitude of the acting force, the initial length l and inversely proportional to the cross-sectional area S:

Δl = (l × P) / (E × S) or p = E × ε,

where p = P / S - voltage; ε = Δl / l - relative longitudinal deformation.

Materials are divided into brittle and ductile. Brittle substances break at very low relative elongations. Brittle materials usually withstand, without breaking, greater compression than tension.

Together with tensile deformation, a decrease in the diameter of the sample is observed. If Δd is the change in the diameter of the sample, then ε1 = Δd / d is usually called the relative transverse strain. The absolute value μ = ε1 / ε is called the transverse deformation coefficient - Poisson's ratio . Poisson's ratio for steel: μst = 0.3.

Shear is a deformation in which all layers of a body parallel to a certain plane are displaced relative to each other.

Hooke's law for shear deformation: р = G × α, where G is the shear modulus; α—shift angle (relative shift). Modulus of elasticity of steel in shear: Gst = 0.8×10 5 MPa.

The relationship between the elastic constants: G = E / 2 × (1 + μ).

The temperature coefficient of linear expansion is a value equal to the average (in the temperature range [0; t] °C) relative elongation of the body (deg -1): α = (l1 – l) / (t × l). Temperature coefficient of linear expansion: for steel, αst = (11-12)×10 -6 deg -1; for copper, αm = 16.5×10 -6 deg -1; for aluminum, αal = 23.0×10 -6 deg -1.

The absence of thermal gaps leads to the emergence of significant forces determined by the cross-sectional area of ​​the shaft:

where E is Young’s modulus, MPa; S—shaft cross-sectional area, m2; α - coefficient of linear expansion, deg -1; Δt—temperature increase, °C.

Yield strength is the stress at which yielding occurs (an increase in deformation without an increase in the deforming force). Yield strength: ordinary steel, σt = 200 MPa; medium strength steel, σt = 400 MPa; alloy steel, σt = 800 MPa.

The elastic limit is the stress at which residual deformations first reach a certain value, characterized by a certain tolerance established by technical conditions.

Ultimate strength is the stress corresponding to the greatest load preceding the failure of the sample.

Fatigue is the process of gradual occurrence and development of a crack in a material under the influence of repeated force impacts.

Fatigue limit is the greatest stress that a material can withstand for a given number of loading cycles.

Creep is an increase in time of plastic deformation of a material under force impacts less than those that cause permanent deformation.

Elastic modulus of different steel grades

Spring steel alloys have the greatest ability to resist deformation. These materials are characterized by high yield strength. The value shows the stress at which the deformation increases without external influences, for example, when bending and twisting.

The elasticity characteristics of steel depend on alloying elements and the structure of the crystal lattice. Carbon imparts hardness to the steel alloy, but in high concentrations it reduces ductility and springiness. The main alloying additives that increase elastic properties: silicon, manganese, nickel, tungsten.

Often, the desired indicators can be achieved only with the help of special heat treatment modes. In this way, all fragments of the part will have uniform fluidity indicators, and weak areas will be eliminated. Otherwise, the product may break, burst or crack. Grades 60G and 65G have such characteristics as tensile strength, viscosity, wear resistance, they are used for the manufacture of industrial springs and musical strings.

The metallurgical industry has created several hundred grades of steel with different elastic moduli. The table shows the characteristics of popular alloys.

Table of strength moduli of steel grades

Modulus of elasticity for metals and alloys

Elasticity of steels

How to Dry Dates at Home

Hello, friends! When we decided as a family that we would gradually give up refined sugar. We tried one thing and then another, but everything is not so simple, because our body does not tolerate “emptiness” at all. I had a habit of eating candy when I drank tea, and it still remains that way. But I found an alternative, so today we will talk about how much sugar is in dried dates and can this product replace such familiar sweet snacks?

How to store dates

Date palm fruits are extremely healthy and tasty products. If you have a sweet tooth, they will come to your rescue by successfully replacing harmful sugar. They contain large amounts of fructose; this sweetness can be consumed even if you have diabetes. The value of the product is in a huge amount of microelements and vitamins; the fruit is rightly called a product that prolongs life.

Interesting: How to preserve horseradish for the winter at home

It is known that by eating only 10 fruits during the day, you will never suffer from heart disease, hypertension and other unpleasant ailments. Dates stimulate intestinal function, improve digestion, and prevent weight gain. They are not allergens, so they can be given to children without fear. The powerful antitumor effect of this valuable dried fruit prevents oncological processes from developing, so buy dates and introduce them into your daily diet. At home, the fruits are stored well and for quite a long time, and they do not require special conditions.

But we will still tell you how to store dates in order to preserve their valuable properties as much as possible in a home or city apartment.

Can dates be used for weight loss?

At the heart of every weight loss is one simple truth: you need to spend more energy than you consume in the form of food. Therefore, if you uncontrollably eat dates, which are very high in calories, you will probably not be able to lose weight. After all, 100 grams of product contains 227 kcal.

• Carbohydrates - 69.2 g.
• Fat - 0.5 gr.
• Proteins - 2.5 g.

To really lose weight while enjoying this amazing dried fruit, you just need to know the peculiarities of your metabolism and use a quality product, not one processed with sugar syrup.

The sticky and shiny fruits are similar in properties to caramels. In addition, knowing the high calorie content, you should limit your intake. At the same time, you can eat date bars and candies as a snack or a substitute for sweet chocolate bars.

Can you eat dates for gastritis?

• If you have gastritis, dates can be consumed if you follow a number of rules regarding the diet in the presence of this disease (small meals, light and non-aggressive warm food, caution in consuming raw fruits and vegetables).
• Particular caution when including dates in the diet of a patient with gastritis is necessary due to the content of dietary fiber in the fruit, which, when consumed in moderation as recommended by a doctor, is beneficial for the functioning of the gastrointestinal tract, and in case of uncontrolled use in food, coarse fiber and protein can have a negative effect .
• In no case should you eat dates in case of exacerbation of the disease; during remission, the norm determined by the doctor will be beneficial, especially with high acidity, since date acids and amino acids have a positive effect on restoring the acid-base balance, preventing heartburn.
• On average, the norm is to take 50 g of dates at a time shortly before the main meal.
• You can also prepare desserts, cocktails, puddings, compotes and smoothies , and add them to pilaf.

For example, a dessert of dates with honey is useful for gastritis: chop the fruits, mix with honey until the consistency is not very thick and eat one dessert spoon on an empty stomach. You can also add chopped dried apricots here.

Dates: calories

• It depends on the form in which you use it. In fresh it is 274 kcal, and in dried - 340 kcal. If you keep in mind that the average weight of one date is about 10 grams, then it contains approximately 23-24 kcal.
• Dried dates are similar in calorie content to dried dates. Moreover, regardless of the processing method, the fruit retains all its beneficial properties. And despite the fairly high calorie content, it is still more healthy and preferable than sugar, sweets or cakes.
• It should also be noted that dates with pits are higher in calories than those in which the pits have been removed. The presence or absence of a seed depends on the drying technology. Fruits with seeds retain more nutrients and, on average, have 10 kcal more calories.

For comparison, the average calorie content of a fresh date with a pit (per 100 g) is 240 kcal, a dried date with a pit is 283 kcal, without a pit is 274 kcal, and a dried date with a pit is 292 kcal.

Date pits: benefits

• Date seeds also have medicinal properties. In order to prevent the appearance of stones in the kidneys and bladder , as well as to facilitate their removal, a special decoction is prepared that can be drunk along with the main treatment. And, of course, it is advisable to inform your doctor about this.
• If you grind date seeds into powder , it will help treat festering wounds and ulcers on the skin. This powder is also effective in combating diarrhea.

Even their bones are incredibly useful votes
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What are dates?

The date palm is native to the Persian Gulf, and the plant was known about 6,000 years ago. This tree is tall, with very large elongated leaves and fruits up to 7 cm long and 2 - 3 cm in diameter. Inside the oblong fruit there is a stone 6 - 8 mm. When unripe, dates are either bright red or yellowish. There are a lot of varieties in the world - 1500.

Today, the main supplier is Saudi Arabia, although date palms are the second bread in many Islamic countries and are grown everywhere: Iraq, North Africa, Morocco, South Africa. Now the date palm has already been brought to Australia. This dried fruit is also becoming more and more popular here.

• Chinese date. It has several other names: unabi and jujube. Mostly used in Asian countries: Japan, China and Indochina. The taste is most pronounced when the fruit sits for a while. It is dried when it is most aromatic. Although it can be used both fresh and dried. The fruits are very fleshy and nutritious. Often used in spices, sauces and national dishes.
• Canary. Serves more as a decorative decoration. It is also used as a remedy for burns and skin diseases.

Classification of dates

This fruit is divided into groups depending on the softness and oiliness of the fruit:

• soft;
• semi-dry;
• dry.

The structure and ripeness of the fruit may contain completely different types of sugar:

1. Dates with soft flesh can spoil quickly, so they are dried. They contain invert sugar, consisting of fructose and dextrose.
2. Semi-dry and dry are made from cane sugar and contain much less moisture.

A fully ripened date is a golden-brown fruit with a matte and wrinkled skin, reminiscent of chocolate candy and a sweetish, spicy taste. By the way, if its skin is shiny and peels off easily, it means that before transportation and sale it was soaked in sugar syrup or other preparations in order to preserve and extend its shelf life. Therefore, before purchasing, be sure to carefully examine the fruit.

Dates and diabetes

This product has a high glycemic index and is therefore strictly not recommended for those suffering from this disease. GI - 70 is a fairly high indicator. And depending on the variety of dates, the amount of sugar varies from 103 to 165 units, which is unacceptable for people with diabetes.

Contraindications

1. This product is also not recommended for obese people.
2. It is worth limiting consumption if you have an individual intolerance or allergic reactions to one of the components contained in dates.
3. It is recommended to give children over 3 years of age no more than 1 to 3 pieces per day.
4. For gastritis, stomach ulcers and problems with the pancreas, dates are contraindicated.

So, dates are very healthy and enrich the body with many useful elements, but it is worth consuming these dried fruits in doses, even if you replace refined sugar with them.

We read about how much sugar there is in marshmallows here.

If you have anything to add to my list of beneficial properties of dates, write in the comments. I will be glad to communicate

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Useful properties of dates

Many, especially adherents of a healthy diet, eat these fruits instead of sweets and candies. They are not only tasty, but also very healthy. Let's consider what is included in the composition of this dried fruit, because this is the form in which we can purchase them.

Cellulose

If you eat just one small cup of fruits a day, either whole, or as an addition to dishes (for example, instead of raisins, to give a specific “oriental” taste), then the body receives almost half of the fiber requirement per day.

A cup of fruit contains 11.8 g of protein and 47% fiber. These dietary fibers have a beneficial effect on the functioning of the digestive system, and also significantly reduce the level of “bad” cholesterol in the blood and normalize sugar levels. They are useful for people suffering from constipation, as they have a laxative effect.

Vitamins and minerals

The date can rightfully be considered a storehouse of useful substances. And most importantly, they are found in the fruit in a fairly high concentration (we are considering a small cup and a percentage of the daily value):

• 12% - vitamin B6;
• 8.6% - vitamin B5;
• 9% - niacin (vitamin B3 or PP, nicotinic acid, which plays a very important role in all redox processes, is involved in the formation of enzymes and the metabolism of lipids and carbohydrates in living cells);
• 5.7% - riboflavin;
• 4.5% - thiamine;
• 7% - folic acid;
• 8% - iron.

By eating just a few dates as a snack, you can well refuel your body with a whole range of healthy and essential vitamins. This is just one group of elements, and also includes calcium, magnesium, potassium, phosphorus, copper, manganese, and selenium. As you can see, almost the entire table of vitamins and minerals necessary for health.

Dates - for the heart and against cancer

Scientists have found that dried fruits, and these fruits especially, contain the highest concentration of polyphenols, which have a beneficial effect on the functioning of the cardiovascular system and reduce the risk of cancer. This is a powerful antioxidant protection for the entire body. Therefore, pediatricians advise eating at least small amounts of these healthy foods.

Tryptophan

This amino acid is also part of the dried fruit and helps fight depression, insomnia, improves memory and mood. Normalizes brain function.

Oxytocin

This substance, which is included in the fetus, helps bring the uterus to a normal state after labor and helps increase lactation.

Retinol

This substance contained in dates gives shine and health to hair, and nails will always be in order if you eat at least a small amount of the product per day.