10 sources of cracking in concrete you should know

10 sources of cracking in concrete you should know

We all understand cracking is one in all the most important issues in concrete and it ought to be thought of whereas combine style, except for that, we've to grasp the sources that can cause cracking in concrete. Here may be a list of sources of cracking in concrete.

Sources Of Cracking In Concrete

Use of low-grade materials:

One of the most important sources is that the use of lower quality materials that embody each concrete and steel in ferroconcrete structures.

Shrinkage:

Shrinkage will cause cracking if not controlled throughout combine style and solidification stage. Shrinkage will become important in high strength concrete thanks to low water/cement magnitude relation and additionally thanks to use of Mineral Admixtures.

Quality and Type Of Aggregate:

The quality of mixture employed in concrete determines the general strength of concrete. If the combination is of poor quality it'll not build a correct bond with cement.

Overloading of structure:

The Overloading of structures particularly at younger age may be  common supply of cracking. This can happen if formwork is removed before time or additional construction load is gift.

Mistakes at design stage in office:

If there area unit errors at style stage then it's obvious that issues can occur at website. concrete cracking is one of them.

Improper Curing:

Another major cause of concrete cracking. If curing is not done appropriately for given time span then one should expect cracking.

Early Formwork Removal:

If the formworks is removed before concrete has achieved strength, there will be cracking.

Use of Congested Reinforcement in Lean Concrete:

If you use heavy reinforcement in average quality concrete then stress distribution between steel and concrete can become non-linear causing cracking.

Mistakes at Site or during erection:

Proper and trained labour and acquisition area unit necessary for any website work. Lack of it during concreting can cause cracking.



Follow on facebook--@KDLEARNERS

Read More

Corrosion

Corrosion

                         Corrosion

INTRODUCTION:
Corrosion is an undesirable phenomena or process. Due to the corrosion there is limitation of progress in
many the area. The cost of replacement of the  materials and equipment lost through corrosion is
unlimited.
Metals and alloys are used as fabrication or construction materials in engineering. If the metals or alloy structures are not properly maintained, they deteriorate slowly by the action of atmospheric gases, moisture and other chemicals. This phenomenon of destruction of metals and
alloys is known as corrosion.
Corrosion of metal is defined as spontaneous destruction of metals in the course of their chemical, electro-chemical or bio-chemical interaction with the environment. Thus, it is exactly the reverse of the extraction of metals from the ores.
Example: Rusting of iron
A layer of reddish scale and powder of oxide (Fe3O4) is formed on the surface of the iron metal.
A green films of the basic carbonate [CuCO3 + Cu(OH)2] is formed on the surface of copper, when it is exposed to moist-air containing carbon dioxide.

CONSEQUENCES (EFFECTS) OF CORROSION:

The economic and social consequences of corrosion include
i) Due to formations of the corrosion product over the machinery, the efficiency of the machine gets failure leads to plant shut down.
ii) The product contamination or losses of products due to corrosion.
iii) The corroded equipments must be replaced
iv) Preventive maintenance like the  metallic coating or organic coating is required.
v) Corrosion releases toxic products.
vi) Health (eg., from the pollution due to a corrosion product or due to escaping chemical from a corroded equipment).

CAUSES OF CORROSION:

In nature, metals occur in two different forms.

1) Native State (2) Combined State

Native State: The metals exist as such in the earth crust then the metals are present in a native state.Native state means free or uncombined state. These metal the are non-reactive in nature. They are the noble metals which have very good corrosion resistance. Example: Au, Pt, Ag, etc.,

Combined State: -Except noble metals, all other metal are the highly reactive in nature which the undergoes the reaction with their the  environment to form the stable compound called ores and minerals. This is combined state of metals. Example: Fe2O3, ZnO, PbS, CaCO3, etc.,

Metallic Corrosion: The metal are extracted from their metallic compounds (ores). During  extraction, ores are reduced to their the  metallic states by applying energy in form of various process. In pure metallic state, the metals are the unstable as they are considered in excited states (higher energy state). Therefore as soon as the metals are extracted from their ores, the reverse process begin and form the metallic compounds, which are the thermodynamically stable (lower energystate). Hence, when metals are used in various forms, they are exposed to the environment, the exposed metal surface begin to the decay (conversion to more stable compound). This is the basic reason for metallic corrosion.

Corrosion-Oxidation

Metal Metallic Compound + Energy

Metallurgy-Reduction

Although corroded metal is the  thermodynamically more stable than the pure metal but due to corrosion, useful properties of a metal like malleability, ductility, hardness, luster and electrical conductivity are lost.

CLASSIFICATION OR THEORIES OF CORROSION

Based on the environment, corrosion is classified into

(i) Dry or Chemical Corrosion .

(ii) Wet or Electrochemical Corrosion.

For more detailed about corrosion download pdf by clicking below download button

All detailed concept of corrosion - Download PDF

Read More

THE SECRETS OF LEARNING MATH

THE SECRETS OF LEARNING MATH

THE SECRETS OF LEARNING MATH

There are essentially two secrets to learning mathematics; the first is concerned with the content and the other with teaching. There is far too much content at each grade level, and every few years the amount of content is increased. Under these conditions, students are urged to memorize concepts without understanding in order to maintain an acceptable grade level on tests. Research has determined that, for most math students, the memorization of concepts without understanding is stored in the short-term memory and soon forgotten. The first secret to student success in math is to reduce the amount of content at each level so that there is time to learn and understand the concepts.


The second secret is one concerned with teaching. I have often heard that in the history of education, the "best" education took place in the one-room schoolhouse. If this is true, then it is because in a one-room schoolhouse education often came about as a result of older students teaching younger ones; both students gain from this experience. When a student is able to explain in his or her own words a math concept, that student understands the concept. The second secret to student success in learning math is to have students understand math concepts and demonstrate their understanding the concept by correctly explaining it in their own words to someone else.

THE SECRETS OF LEARNING MATH

The predominate guideline for mathematics curriculum the past few decades has been acceleration and this has resulted in all math courses having too much content. This means that most students must memorize math to pass the course. Unfortunately memorizing is short-term and not related to understanding mathematics.

Conclusions from the Research

              Conclusions from the Research

There seems to be two main factors that could be corrected in our teaching of math courses that would go a long way toward eliminating the current problem. These two factors are memorization and acceleration.

Memorization:

                      Memorization

Students are trying to memorize all necessary facts that are needed to pass the course. Unfortunately, this is not possible for most students and such a course of action has no long-term benefits; hence causing the basic problem in mathematics.

Acceleration:

THE SECRETS OF LEARNING MATH

We are attempting to teach too much too fast in math courses. This, in turn, causes students to rely on memorization as their best hope to pass the course. We do not give them the proper amount of time to understand concepts, which reduces the need for memory.

Read More

LIST OF P.S.U. THAT RECRUIT CIVIL ENGINEERS BASED ON GATE SCORE

LIST OF P.S.U. THAT RECRUIT CIVIL ENGINEERS BASED ON GATE SCORE

LIST OF P.S.U. THAT RECRUIT CIVIL ENGINEERS BASED ON GATE SCORE

HERE IS THE LIST OF ALL PSUS THAT RECRUIT CIVIL ENGINEERS THROUGH GATE EXAM.

 

1. AIRPORTS AUTHORITY OF INDIA

2. BARC 

3. BSPHCL

4. CEL

5. EDCIL(EARLIER EDUCATIONAL CONSULTANTS INDIA LIMITED) 

6. HAL

7. HPCL

8. IOCL

9. IRCON

10. KRIBHCO (KRISHAK BHARATI COOPERATIVE LTD)

11. MRVC(MUMBAI RAILWAY VIKAS CORPORATION LTD.) 

12. NALCO

13. NATIONAL BUILDINGS CONSTRUCTION CORPORATIONLTD. (NBCC)

14. NATIONAL FERTILIZERS LIMITED NFL

15. NATIONAL HIGHWAYS AUTHORITY OF INDIA (NHAI)

16. NATIONAL HYDROELECTRIC POWER CORPORATION(NHPC LIMITED) 

17. NUCLEAR POWER CORPORATION OF INDIA LIMITED(NPCIL)

18. NLC (NEYVELI LIGNITE CORPORATION LIMITED)

19. ODISHA POWER GENERATION CORPORATION LTD.(OPGC)

20. POWER GRID CORPORATION OF INDIA LIMITED – PGCIL 

21. PUNJAB STATE POWER CORPORATION LTD. (PSPCL)

22. PUNJAB STATE TRANSMISSION CORPORATION LIMITED – PSTCL

23. RITES

24. RVNL

25. TEHRI HYDRO DEVELOPMENT CORPORATION INDIA LIMITED ( THDC INDIA LTD )

26. WEST BENGAL STATE ELECTRICITY DISTRIBUTION COMPANY LIMITED (WBSEDCL)

Read More

HOW QUALITY OF CEMENT IS CHECKED AT SITE

HOW QUALITY OF CEMENT IS CHECKED AT SITE

Cement is probably the costliest ingredient in concrete. Strength of Concrete structures is largely affected by quality and type of cement used in construction. 

HOW QUALITY OF CEMENT IS CHECKED AT SITE

Both from economic and safety point of view it is very much advicable to check the quality of cement by thorough inspection. In this post we are going to discuss some simple yet useful methods that are very popular for this purpose and are commonly used in sites.

HOW QUALITY OF CEMENT IS CHECKED AT SITE

Lets discuss them one by one.

1. DATE OF PACKAGING:

Strength of cement reduces with time. So the date of packing given by manufacturer should be checked prior to buying. Cement should be used before 90 days from packaging date. For a better clarity the percentage of lose in strength of cement with respect to time is given in the following table.

QUALITY OF CEMENT

2. COLOUR OF CEMENT:

Cement of good quality has gray colour with greenish shade. The colour should be uniform throughout.

3. CHECK FOR LUMPS:

No lumps should be present in the cement. Lumps are formed due to absorption of moisture from the climate.

4. RUBBING TEST:

Cement should feels smooth while the rubbing in between fingers. If it  gives the rough feeling that mean cement is mixed with the sand.

5 TEMPERATURE TEST:

Simply inserts your hand into cement bag, It should give cool feeling if its quality is good. Otherwise, you may feels warm because of the hydration reaction.

6. FLOAT TEST:

Take some amount of the cement and throws  it in water. The cement should floats for sometimes before it sinks in water.

7. SETTING TEST:

Make a thick cement paste with the water and immerse it in water for 24 hour. It should be sets and should not develops cracks.

8. STRENGTH TEST:

Prepares a cement block of 25 mm x 25 mm and 200 mm in the length. Now submerge it in the water for seven days. Now place it on the supports 15cm aparts and load it with the 34 kg weight. Block mades from good cement will not show the any signs of failure.

Read More

Computer Network and its Type

 Computer Network and its Type

What is computer network:-

computer network

A electronic network could be a assortment of computers and different hardware parts interconnected by communication channels (cables or satellites) that permit sharing of resources and data. This session introduces you to the {fundamental} fundamental ideas of networking and net and victimisation differing kinds of net affiliation.

Networks are designed using the following architecture:

Peer-to-peer (P2P)
Networks within which all computers have associate equal standing square measure known as peer to see networks. Generally in such a network every terminal has associate equally competent processor.

Client- Server
Networks within which sure computers have special dedicated tasks, providing services to other computers (in the network) are called client server networks. The computer(s) which give services square measure known as servers and therefore the ones that use these services square measure known as shoppers.

Types of networks

There are two major types of network Local Area Network (LAN) and Wide Area Network (WAN).

 Computer Network and its Type

Local Area Network

A local space network (LAN) is one network  that connects computers or desktops and devices in a very restricted geographic area like home, school, computer laboratory, office building, or closely positioned group of buildings.
Usually native space networks provide terribly high speeds and square measure used for connecting computers and peripherals like printers, scanners, etc.

Wide Area Network

A wide space network (WAN) is one that covers a broad space (i.e., any network that links across metropolitan, regional, or national boundaries). The Internet is that the hottest WAN, and is employed by businesses, governments, non-profit organizations, individual shoppers, artists, entertainers, and lots of others.

Read More

Civil Engineering

Civil Engineering

Who is Civil Engineer:

Civil Engineering

A civil engineer is an engineer who usually works on public and government projects. The occupation in recent times has been divided into several different fields. This is guide will give you salary information and a brief outline in what you can expect when entering this field.

Education:

Civil engineer required to have graduate from a post secondary college with the degree in civil engineering, which requires a strong backgrounds in mathematics and the physical science. This degree will usually be a 4-year degree, though many civil engineers study further to obtain a masters, engineer, doctoral and post doctoral degrees. In some areas, civil engineers are required to have a license. People who do not obtain the license may not call themselves "civil engineer."

Work Environment:

civil engineering works

The primary responsibility for a civil engineer is to check the site before starting or permitting any work to start. Ensuring that the construction site is free from all potential dangers and has been cleared, he has to work tediously on the project for safety and quality assurance. Usually the civil engineer would discuss in detail the requirements and if necessary will consult with his other counterparts and superiors on the project like the architects and contractors. This will require a degree of people skills in order to communicate well with other professionals assigned to the project.

civil engineer jobs

Another important part of your job will be preparing the designs and blueprints of the project for the various construction works. Again, you will have to coordinate your work with the head architect on the project.

Salary Information:

civil engineering salary

Your ability to the  performs all these task well will basically determine your civil engineerings salary. The average salary of a civil engineer is around $75,000. As with all fields the more experience you have, the higher your salary will be. A highly experienced and qualified engineer can command as much as $120,000 per year.

Finally, make sure you take full advantage of government grants and assistance. The current administration has expressed interest in helping students who end up working for the government and pay off their student loans which is a great plus. You can also complete some of your basic courses online which helps if you are strapped for time. This field is very stable and secure with a low rate of unemployment. This is especially important in these hard economic times. With a little of your own research and groundwork, you should have no problem getting started in this exciting career.

Also like - Difference between civil engineer and an architecture

Read More

Difference between an ENGINEERS AND an ARCHITECTURE?

Difference between an ENGINEERS AND an ARCHITECTURE?

What is the Difference between an ENGINEERS AND an ARCHITECTURE?

The major distinctions or difference  between architects and engineers run along generalist and specialist lines. The generalists are ultimately responsible for the overall planning.

It is for this reason that an architecture is generally employed as the prime professional by a client. On some special projects, such as dams, power plants, wastewater treatment, and research or industrial installations, where one of the engineering specialties becomes the predominant feature, a client may select an engineering professional or an E/A firm to assume responsibility for design and construction and taken on the lead role.

Difference between an ENGINEERS AND an ARCHITECTURE

Difference between an ENGINEERS AND an ARCHITECTURE

On certain projects, it is the unique and imaginative contribution of the engineer that may make the most significant total impact on the architectural design.

The overall strength of a dynamic, exposed structure, the sophistication of complex lighting systems, or the quiet efficiency of a well-designed mechanical system may prove to be the major source of the client’s pride in a facility. In any circumstance,  responsibilities of  professional engineer for competence and contribution are just as important to the project as those of the

architecture.

Difference between an ENGINEERS AND an ARCHITECTURE

Difference between an ENGINEERS AND an ARCHITECTURE

Engineers, for example, play a major role in the intelligent building system design, which involves the  mechanical-electrical systems. However, a building’s intelligence is also measured by way it responds to people, both on the insides and outsides.

The systems of the building must meet the functional needs of the occupants as well as respect the human response to temperature, humidity, airflow, noise, light, and air quality. To achieve the multifaceted goals, an intelligent building requires an intelligent design process with respect to design and system formulation as well as efficient and coordinated execution of design and technical documentation within the management structure.

An intelligent building begin with the  intelligent architecture—the shape, building enclosure, and the way the building appears and functions. The optimal building solution can be achieved through a design process that explores and compares varying architectural and the engineering options in concert.

Sophisticated visualization and the analytical tools using three-dimensional computer modeling techniques permits architectures and engineers to rapidly evaluate numerous alternatives. Options can be carefully studied both visually and from a performance standpoint, identifying energy and life-cycle cost impact. This enables visualization and the technical evaluation of multiples schemes early in the design phase, setting basis for an intelligent building.

In all cases, the architect’s or engineer’s legal responsibilities to the client remain firm. The prime professionals is fully responsibles for services delivered. The consultants, in turn, are responsible to the architect or engineer with whom they contract.

Following this principle, the architecture or engineer is responsible to clients for performance of each consultant. Consequently, it is wise for architects and engineers to evaluate their expertise in supervising others before retaining consultants in other areas of responsibility.

the difference between civil engineers and architects

Difference between an ENGINEERS AND an ARCHITECTURE

difference between civil engineering and architecture

Difference between an ENGINEERS AND an ARCHITECTURE

Read More

Classification Of Surveying(Survey-Types)

 Classification Of Surveying

Different Type of surveying

What Are The Classification Of Surveying?

Surveying may be classified on the following basis:

(i) Nature of the survey field
(ii) Object of survey
(iii) Instruments used and
(iv) The methods employed.

                      Classification Of Surveying

• Classification Based on Nature of Survey Field

On this basis survey is also classified as land survey, marine or hydraulic survey and astronomical survey.

• Land Survey. It involves measurement of various objects on land. This type of survey is also more classified as given below:

 (a) Geographics Survey or geographical survey : it's meant for plotting natural options like rivers, lakes, forests and hills as well as man made features like roads, railways, towns, villages and canals.

(b) Cadestal Survey: It is for marking the boundaries of municipalities, villages, talukas, districts, states etc. The survey created to mark properties of people additionally return beneath this class.

(c) town Survey: The survey created in reference to the development of streets, water supply and sewage lines fall under this category.

• Marine or Hydrographic Survey. Survey conducted in ocean depth of water at numerous points in bodies of water like sea, river and lakes fall under this category. Finding depth of water at specific points is thought as sounding.
• Astronomical Survey. And observations created to heavy bodies like sun, stars etc., to the locate absolute position of points on the earth and for the purpose of calculating local time is known as astronomical survey.

• Classification Based on Object of Survey:-

On the idea of object of survey the classification are often as engineering survey, military survey, mines survey, geological survey and archeological survey.

(a) Engineering Survey: the target of this kind of survey is to gather knowledge for planning applied science comes like roads, railways, irrigation, water supply and sewage disposals. These surveys are further sub-divided into:

Reconnaissance Survey for determining feasibility and estimation of the scheme.

Preliminary Survey for aggregation additional info to estimate the price of the project, and

Location Survey to line the work on the bottom.

(b) Military Survey: This survey is supposed for understanding plans of strategic importance.

(c) Mines Survey: this can be used for exploring mineral wealth.

(d) geologic Survey: This survey is for locating completely different strata within the earth’s crust.

(e) archaeologic Survey: This survey is for unearthing relics of antiquity.

• Classification Based on Instruments Used

                                     

Surveying equipment

Based on the instruments used, surveying may be also classified as:

(i) Chain survey

(ii) Compass survey

(iii) Plane table survey

(iv) Theodolite survey

(v) Tacheometric survey

(vi) trendy survey mistreatment electronic distance meters and total station

(vii) Photographic and Aerial survey

The survey is schooled to students chiefly supported this classification.

• Classification Based on Methods Employed

On this basis measure is assessed as triangulation and traversing.

(i) Triangulation: during this methodology management points ar established through a network of triangles.

(ii) Traversing: during this theme of creating management points consists of a series of connected points established through linear and angular measurements. If the last line meets the place to begin it's known as as closed traverse. If it doesn't meet, it's referred to as open traverse.

Read More

Surveying, its objects and Uses

Surveying, its objects and Uses

What Is Surveying and What Are The Objects And Uses Of Surveying?

                    Surveying

Surveying is the art of taking measurements of objects on, above or beneath the ground level to show their relative positions on paper. The relative positions required is either be horizontal, or vertical, or both.

                  Surveying

Surveying, its objects and Uses

Less precisely the term Surveying is used to the measurements of object in their horizontal position. And measurements to deteremine their relative vertical position is known as levelling.

OBJECTS AND USES OF SURVEYING

As states in the definition, object of surveying is to show the relative positions of various objects of an area on paper and produce a plan or map of that area. Various uses of surveying are listed below in details:

               Surveying

• (i) Plans prepared to the record property lines of private, public and government lands helps in avoiding unnecessary controversies.
• (ii) Maps prepared for marking the boundaries of countries, states, districts etc., avoid disputes.
• (iii) Locality plans help in identifying the location of houses and the offices in the area.
• (iv) Road maps help the travellers and the tourist.
• (v) Topographic maps showing natural features like rivers, streams, hills, forests helps in planning irrigations projects and flood control measures.
• (vi) For the planning and estimatings the project work like as roads, bridges, railways, airports, water supplies and waste water disposal surveying is required.
• (vii) Marine surveys and hydrographic survey helps in planning the navigation routes and harbours.                                        

Surveying, its objects and Uses   

Surveying-equipments

• (viii) Military surveys is required for the strategic planning.
• (ix) Mine surveys area unit needed for exploring mineral wealth.
• (x) Geological surveys are necessary for determining the different strata in the earth crust so that proper location is found for reservoirs.
• (xi) Archeological surveys are useful for the unearthing relics of antiquity.
• (xii) Astronomical survey helps in study of movements of planets and for calculating local and standard times.

• http://eunsetee.com/Y0zx

Read More

Stress-Strain Curve

STRESS - STRAIN CURVE FOR BRITTLE MATERIALS BASIC INFORMATION

What Is The Stress-Strain Curve Of Brittle Materials?

Many of  characteristics of a material can be deduced from  tensile test. It is more convenient to compare materials in terms of stresse and strain, rather than loads and extensions of a particular specimen of a material.

The stress at any stage is the ratio of the load of the original cross-sectional of  area of the test specimen; the strain is the elongation of a unit length of the test specimen.

For stresses up to about 750 MN/m2 the stress-strain curve is linear, Showing that the material obeys Hooke’s law in this range, the material is also elastic in this range, and no permanent extension remains after removal of the stresses.

The ratio of stress to strain for this linear region is usually about 200 GN/m2 for steel; this ratio is known as Young’s modulus and that is denoted by E. The strain at  limit of proportionality is of order 0.003, and is small compared with strains of the order 0.100 at fracture.
 

Stress-Strain Curve

We note that Young’s modulus has the units of a stress, the value of E define the constant in  linear relation between stress and strain in elastic range of material. We have

 Stress-Strain Curve Of Brittle Materials

 for the linear-elastic range. If P is total tensile load in a bar, A its cross-sectional area, and Lo its length, then

 Stress-Strain Curve

where e is extension of length Lo. Thus the expansions is given by

 Stress-Strain Curve

Stress-Strain Curve

If the material is stressed beyond linear-elastic range of the limit of proportionality is exceeded, and the strain increase non-linearly with the stress. Moreover, removal of stress leaves the material with some permanent extension; h range is then both non-linear and inelastic.

The maximum stresses attained may be of order of 1500 MNlm, and the total extension or elongation, at this stage may be of order of 10%. The curve of Figure 1.5 is typical of behaviour of brittle materials as for example, area characterized by small permanent elongation at the breaking point, in the case of metals this is usually Lo%, or less.

When a material is stressed beyond limit of proportionality and is then unloaded permanent deformations of the material take place. Suppose tensile test-specimen of Figure 1.5 is stressed beyond the limit of proportionality, to a point b on the stress-strain diagram. If the stress is now remove, the stress-strain relation follow the curve bc, when the stress is completely remove there is a residual strain given by intercept Oc on the &-axis.

If stress is applied again, the stress-strain relation follow the curve CD initially, and finally  curve df to the breaking point. Both the unloading curve bc and reloading curve cd are approximately parallel to the elastic line Oa, they are curved slightly in the opposite directions.

 hooke 's law - https://kdlearners.blogspot.com/2019/10/hookes-law.html

Stress-Strain Curve

Stress-Strain Curve

The process of unloading and reloading, bcd, had little or no effect on stress at breaking point, the stress-strain curve the being interrupted by only a small amount bd, Figure 1.6. The strains -stresses curve of brittle material for tension and the compression are usually similar in form, : although the stress at the limit of proportionality and at fracture may be very different for two loading condition.

Typical tensile and the  compressive stress-strain curve for concrete are shown in Figure 1.7;  the maximum stress attainable in the  tension is only about one-tenth of that in the  compression, although the slope of the stress-strain curve in the region of zero stress are nearly equal.


Related post - https://kdlearners.blogspot.com/2019/10/hookes-law.html

Read More

HOOKE’S LAW

HOOKE’S LAW; MODULUS OF ELASTICITY BASIC INFORMATION

What Is Hooke's Law? How To Apply Hooke's Law?

Most engineering structures are designed to undergo relatively small deformations, involving  the straight-line portion of the corresponding stress-strain diagram. For that initial portion of the diagram, the stress s is directly proportional to the strain P, and we can write


σ = ΞE

This relation is known as Hooke’s law, after Robert Hooke (1635–1703), an English scientist and one of the early founders of applied mechanics. The coefficient E is called the modulus of elasticity of the material involved, or also Young’s modulus, after the English scientist Thomas Young (1773–1829).

Since the strain P is a dimensionless quantity, the modulus E is expressed in the same units as the stress s, namely in pascals or one of its multiples if SI units are used, and in psi or ksi if U.S. customary units are used.

The largest value of  stress for which Hooke’s law can be used for a given material is known as proportional limit of that material. In the case of ductile materials possessing a well-defined yield poin, the proportional limit almost coincides with the yield point.

For other materials, the proportional limit cannot be defined as easily, since it is difficult to determine with accuracy the value of the 63 stress s for which the relation between s and P ceases to be linear. But from this very difficulty we can conclude for such materials that using Hooke’s law for values of the stress slightly larger than the actual proportional limit will not result in any significant error.

Some of the physical properties of structural metals, such as strength, ductility, and corrosion resistance, can be greatly affected by alloying, heat treatment, and the manufacturing process used. For example, we note in the stress-strain diagrams of pure iron and of three different grades of steel that large variations in the yield strength, ultimate strength, and final strain (ductility) exist among these four metals.

HOOKE’S LAW

           Hooke's Law

All of them, however, possess the same modulus of elasticity; in other words, their “stiffness,” or ability to resist a deformation within the linear range, is the same. Therefore, if one high-strength steel is substituted for a lower-strength steel in a given structure, and if all dimensions are kept the same, the structure will have an increased load-carrying capacity, but its stiffness will remain unchanged.

For each of the materials considered so far, the relation between normal stress and normal strain, s 5 EP, is independent of the direction of loading. This is because the mechanical properties of everyone material, including its modulus of elasticity E, are independent of the direction considered. Such materials are said to be isotropic.

Hooke's Law

Materials whose properties depend upon the direction considered are said to be anisotropic. An important class of anisotropic materials consists of fiberreinforced composite materials. These composite materials are obtained by embedding fibers of a strong, stiff material into a weaker, softer material, referred to as a matrix.

Typical materials used as fibers are graphite, glass, and polymers, while various types of resins are used as a matrix. Figure 2.12 shows a layer, or lamina, of a composite material consisting of a large number of parallel fibers embedded in a matrix.

            Hooke's Law

An axial load applied to the lamina along the x axis, that is, in a direction parallel to the fibers, will create a normal stress sx in the lamina and a corresponding normal strain Px which will satisfy Hooke’s law as the load is increased and as long as the elastic limit of the lamina is not exceeded.

Similarly, an axial load applied along the y axis, that is, in a direction perpendicular to the lamina, will create a normal stress sy and a normal strain Py satisfying Hooke’s law, and an axial load applied along the z axis will create a normal stress sz and a normal strain Pz which again satisfy Hooke’s law.

However, the moduli of elasticity Ex, Ey, and Ez corresponding, respectively, to each of the above loadings will be different. Because the fibers are parallel to the x axis, the lamina will offer a much stronger resistance to a loading directed along the x axis than to a loading directed along the y or z axis, and Ex will be much
larger than either Ey or Ez.

A flat laminate is obtained by superposing a number of layers or laminas. If the laminate is to be subjected only to an axial load causing tension, the fibers in all layers should have the same orientation as the load in order to obtain the greatest possible strength. But if the laminate may be in compression, the matrix material may not be sufficiently strong to prevent the fibers from kinking or buckling.

The lateral stability of the laminate may then be increased by positioning some of the layers so that their fibers will be perpendicular to the load. Positioning some layers so that their fibers are oriented at 308,
45 deg, or 60 deg to the load may also be used to increase the resistance of the laminate to in-plane shear.

Hooke's Law

Go home page - https://kdlearners.blogspot.com-

http://eunsetee.com/Y0zx

Read More

Computer

Computer

Computer-

                                  

Computer

-Defination of computer:-

                                             Computer is a electronic device that accept dat from user ,processing data by performing calculation and operations on it and generate output as a result for the users.

In simple lauguage we can say that computer is

 

a electronic  machine that is able to take

 

information (as a input) , do some work on it

 

(processing) and make new information

 

(output).

 

A computer is understood to be a device that

 

computes or calculate or compute numbers.

                                                

Compters

Function of computer and some definitions:-

Input:- Informations or data that is enter in computer.

              Means that data which provide to computer to performing operation on it. The most common input devices are keyboard, mouse,magnetic tap readers etc.

Output:- The data which provide computer for user after performing different operation.

It make processed data available to user.

Storage:- It store data and programes.

Computer.

Processing:- It is the sequence of actions taken on data to convert it into information which is meaningful to user.It can be calculations or decesions taken by computer.

Data:-Unprocessed row facts and figure like numbers,text,audio,video etc.

Information:- When data is processed,organized structure and presented in given context so as to useful.

Instructions:- It is the command given to computer in computer lauguage by the user .

Program:- Set of instructions given to the computer in order to perform some tasks.

Hardware:- It is the collections of the physical elements that constituent a computer system.

Simply say - all the physical component of the computer including keyboard, mouse, monitor etc. are the part of hardware.

                                                   

Computer Hardware(keyboard)

                                       

Computer Hardware(Mouse)

Software:- It is the set of programe and processures.

Simply say – software  tells hardware  what to do and how to do.The program and lauguage used by the computer are called software.    

                                  

Computers

Read More