KNOW HOW SPOILERS WORK

Spoilers are added to cars and other vehicles to make them more aerodynamic. Most are attached to the back of the vehicle, above the trunk, on the rear window, on the roof, or on the front. Various types and the positioning of a spoiler can do different things to improve a vehicle’s performance. However, the main reason people install these gadgets is to allow for better airflow over and around the vehicle, which in turn, creates better grip or traction on the road. Vehicles that run at high speeds often encounter control problems because, at high speeds, the increased airflow creates too much lift, which can be especially dangerous when the vehicle makes a turn, as this can make it fly off the road and lose control.

Benefits of a Car Spoiler :-

Installing a spoiler on a vehicle provides a variety of benefits for owners. The main benefits, perhaps, are for better traction and to add a sporty look, but also include other advantages, such as increased fuel efficiency, added visibility, reduced vehicle weight, and braking stability.

 

Benefit 1: Maintain Traction

The main benefit of installing a spoiler on a vehicle is to help it maintain traction at very high speeds. When a vehicle goes very fast (over 70 mph), the air pressure can lift the car, which makes it difficult to maneuver the car without the danger of having it spin out of control. Rear spoilers, in particular, push the back of the car down so the tires can grip the road better and increase stability.

 

Benefit 2: Increase Fuel Efficiency

Front car spoilers or air dams can increase gas mileage in some cars. Since these types of spoilers reduce the drag, instead of increasing it, by pushing the air around the vehicle, it does lower the amount of energy, or fuel, the car needs to burn to propel itself forward.
 

Benefit 3: Added Visibility

Another advantage of installing a rear spoiler on a vehicle is the added visibility, which means other drivers on the road can easily see the vehicle to help prevent rear-end collisions and other types of accidents. Certain spoilers, such as trunk cap spoilers, even have brake lights at eye level so the driver behind can easily be alerted when the vehicle is slowing down or braking.
 

Benefit 4: Reduce Weight

Believe it or not, a spoiler can reduce the weight of a vehicle. While this may seem counterintuitive, it makes sense in a way. The only thing keeping a vehicle stable on the road is its weight. Perhaps that is why many people have this perception that SUVs are much safer because their heavier mass keeps them steady. However, having a spoiler means that the car manufacturer can reduce the weight of the vehicle by using lighter materials or doing away with unnecessary weight without the worry that driving at high speeds causes the car to become unsteady and fly off the highway.
 

Benefit 5: Create a Stylish Look

Most car owners install spoilers as a fashion accessory, and spoilers do a pretty good job of making a vehicle look cool. This idea first became popular in the 1970s, when Porsche introduced the 911 Turbo, which featured whale tail spoilers on the back. Today, many cars come with built-in spoilers to evoke that sporty look, though many aftermarket spoilers are available for a wide variety of car makes and models.
 

Benefit 6: Increase Braking Stability

Adding spoilers that raise the downward force on the back of the vehicle not only increases traction, but the braking ability as well. Drivers have an easier time braking, even at high speeds, making driving even safer.

WELDING DEFECTS

The defects in the weld can be defined as irregularities in the weld metal produced due to incorrect welding parameters or wrong welding procedures or wrong combination of filler metal and parent metal.

Weld defect may be in the form of variations from the intended weld bead shape, size and desired quality. Defects may be on the surface or inside the weld metal. Certain defects such as cracks are never tolerated but other defects may be acceptable within permissible limits. Welding defects may result into the failure of components under service condition, leading to serious accidents and causing the loss of property and sometimes also life.

1. External Defects in welding:

External defects of welding include overlap, undercut, spatter, crater, excessive convexity, excessive concavity, surface porosity, surface cracks.

1.1 Overlap:

Reasons:

• Magnetic arc  blow.
• Excessive size of electrodes.
• Use old small welding speeds during joining of small thickness plates.
• Excessive current conditions.

1.2 Undercut

Undercut area appears like a small notch in the weld interface.
Reasons:

• Use of magnetic arc blows with direct current straight polarity.
• Undersize electrode and insufficient current conditions etc.
• Use of high welding speeds during joining of large thickness plates.
• Excessive arc length.
• Excessive side manipulation.
• Use of damp electrodes.

1.3 Spatter:

During welding operation due to the force of arc, some of the molten metal particles are jumping from weld pool and falling into other areas of the plate is called as spatter.

Reasons:

• Use of low welding speeds during joining of large thickness plates.
• Excessive arc length.
• Use of sample electrodes.

1.4 Crater:

• At the end of welding in Gas Welding, a shallow spherical depression is produced known as the crater.
• crater -This is due to improper welding technique and is formed at the end of weld run.
• This may be remedied by proper manipulation of the electrode. when finishing a weld the operator should not draw away the arc quickly but should maintain the arc without moment until the crater is filled up.
• On re-striking the arc, to continue the weld bead, the arc should strike approximately 15mm in front of the previous bead and travel backwards and then forward the direction of welding.

Reason:

Incorrect torch angle or use of large angle at the end of the weld bead.

1.5 Excessive Convexity:

Reasons:

• Use of low welding speed with direct current reverse polarity.
• excessive current conditions.
• Use of large size electrodes for joining of small thickness plates.

1.6 Surface Porosity:

• Porosity is a group of small voids whereas blow holes or gas pockets are comparatively bigger isolated holes are cavities.
• They occur mainly due to entrapped gases.
• The parent metal melted under the arc tends to absorb gases like H₂, CO, N₂ and O₂ from the atmosphere.
• These gases may also be produced due to coating gradients in the electrode (or) moisture, oil, grease etc., on the base metal. The causes may be summarised as
  • Improper coating of an electrode.
  • Longer arc.
  • High welding currents.
  • Incorrect welding techniques.
  • Electrodes with a damp coating.
  • Rust, oil, grease etc on the job.
• High Sulphur and carbon contents in the base metal.

1.7 Surface Cracks:

Cracks (both external and internal):

• Cracks may be on the microscopic or macroscopic scale.
• They may appear in the base metal, base metal – weld metal boundary or in the weld metal. The crack may be on the weld surface or inside causes are
• The rigidity of the joint (the members are not free to expand or contract).
• Poor ductility of the base metal.
• High sulphur and carbon content of these metal.
• Electrode with the H₂ content.
• The presence of residual stresses.
• Joining of high thermal expansion materials without preheating.
• Joining of high thermal expansion materials without preheating.
• Welding of ferrous materials by using hydrogen as a shielding gas.

2. Internal defects in welding:

Internal defects include slag inclusion, lack of fusion, necklace cracking and incomplete filled groove.

2.1 Slag Inclusion:

• Slag is formed by reaction with the fluxes and is generally lighter.
• It has low density. So it will float on the top of the weld pool. And would chipped off after solidification.
• However, the stirring action of the high-intensity arc would force the slag to go into weld pool and if there is not enough time for it to float, it may get solidification inside the fusion and end up as slag inclusion.

Reasons:

• Use of forehead welding technique in welding.
• Incorrect select of flux powder.
• Improper cleaning of the weld beads in multipass welding.
• Undercut on the previous pass.
• Incorrect manipulation of the electrode. Slag inclusion like property weakens the metal by providing the discontinuities.

2.2 Lack of fusion:

Reasons:

1. Incorrect torch angle in gas welding
2. Insufficient current conditions in Arc welding.
3. Joining of high melting point and high thermal conductivity

2.3 Necklace cracking:

In the case of electron beam weld does not penetrate fully, a blind weld results. In such situations, the molten metal is unable to flow into the penetration cavity and wet the side walls of the workpieces. This will result in cracking, known as “Necklace Cracking” and has been noticed in all materials such as Ti alloys, stainless steels, nickel base alloys and carbon steels.

2.4 Incompletely filled groove:

Occurs in butt welds.
Causes for incompletely filled groove are:

• Inadequate deposition of weld metal.
• Use of incorrect size of the electrode.

10 INTERESTING FACTS ABOUT TOYOTA

1. Toyota Motor Corporation started in 1937 as a division of Toyoda Automatic Loom Works. While the Toyota Group is now best known for its cars, they are still in the textile business as well.

2. The founder of Toyota Motor Corporation actually spells his name T-O-Y-O-D-A. Kiichiro Toyoda, to be exact. The spelling of the company name was changed to Toyota because when it is written in Katakana (a Japanese script) it only takes 8 strokes to write, and 8 is a lucky number in East Asian culture.

3. Kiichiro Toyoda, son of the founder of Toyoda Automatic Loom Works, got ideas for the first Toyota cars from the United States. He traveled to the US in 1929 to investigate automobile production because Japan needed to start producing domestic vehicles due to their war with China. Early Toyota’s bear a striking resemblance to the Dodge Power Wagon and Chevrolet.

4. Even though Toyota started in Japan, the company has created more than 365,000 jobs in the United States.

5. The Korean War saved Toyota. The company was on the verge of bankruptcy, and produced only 300 trucks in June of 1950. In the first few months of the Korean War, the US ordered more than 5,000 vehicles from Toyota, and the company was revived.

6. Toyota first came to America in 1957.

7. In the year 2011, Toyota was ranked as the third largest car manufacturer in the world, behind General Motors and Volkswagen Group.

8. Toyota is the world’s leading manufacturer of hybrid vehicles, and there are more than 1,700,000 Toyota hybrids on the road right now.

9. Toyota invests $1 million dollars every hour in research and development worldwide. They do this in pursuit of building better and safe cars.

10. Eighty percent of Toyotas sold 20 years ago are still on the road today!

INTERVIEW QUESTIONS OF STRENGTH OF MATERIAL

INTERVIEW QUESTIONS OF STRENGTH OF MATERIAL 

1.)What are the units for Poisson’s ratio?

It is a unit less quantity. Because it is one quantity divided by another quantity of the same units.In fact, even the parent quantities that define Poisson’s ratio are unit less. Strain has no units.

2.)What is the difference between Stress and Pressure?
Stress=Resistive force/Area.
Pressure=Force/Area.
Stress is pull force and Pressure is push force.

3.)Difference between Performance and Efficiency?

Performance is the measure of quality of the work done by any machine. better  the quality better will be the performance of that machine. while efficiency is the ratio of desired output to the required input for any machine.

Performance is about the quality that a machine or plant is producing suppose there are two machines, first produces the job of accuracy .002mm and the second one produce product of the accuracy .001mm. then the second one will have higher performance.  while efficiency is the ratio of the o/p to the i/p. if same machines are producing 200 and 100 product per day respectively for the same i/p,then the eff. of the first machine will be high.

4.)What are the causes of main engine black smoke?

There is many cause of black smoke.

a. It’s improper mixture of fuel supply by carburetor like very rich mixture so the fuel improper burn.

b. It’s when piston or piston ring is fail so back side cooling oil release in combustion chamber it cause black smoke.

c. Improper ignition system like not sufficient time of pressure rise delay period.

5.)What is structurally stronger, solid steel or hollow steel?

If a solid and hollow shape have the same outside dimensions, the solid one is clearly stronger.The reason you see so many hollow sections is that they have an incredibly higher strength/weight ratio and can resist the same load with much less material used..

FLUID PROPERTIES

Properties of any material or fluid are used to define its state, condition, behavior and distinguish it from others. There are various types of fluids which behave different in different conditions. For example when we take petrol in a open container, it will evaporate suddenly but the kerosene in same container doesn’t. These all behavior of fluid can be described by its’ properties which knowledge is essential to study about fluid mechanics. 

There are various properties of fluids which are used to define a fluid and its behavior in various fluid applications. These are

Fluid Properties:

Density:

• Density of a fluid is defined as the mass of the fluid per unit volume.
• Mathematically it is defined as the ratio of the mass to the volume of the fluid. 

ρ=  Mass/Volume

• It is depends on the mass and size of the atom of the fluid. Fluids have same volume and different mass have different density. 
• The SI unit of density is Kg/m3. It is generally denoted by ρ

Specific gravity:

• It is density of a fluid compared to the density of water which is 1000 Kg/m3. It shows the substance is how much heavy compare to water. 
• Mathematically it is defined as the ratio of the density of a fluid to the density of water.

S=  (Density of Fluid)/(Density of Water)

• If the value of specific gravity is greater than one it means the fluid is heavy compared to water and if that fluid mix with water the fluid remain downside of the mixture. If specific gravity is less than one means the fluid is light and can flow over the water in a mixture. 
• It is a unit less quantity and shown by the S.

Viscosity:

• The property of fluid due to which, a fluid layer which is flowing with a velocity U, exerts a resistance force on the other layer known as viscosity. 
• It is a property which offers the resistance force in the flow. A fluid has more viscosity has less flow velocity compare to a fluid has less viscosity. For example oil has more viscosity compared to water.
• Viscosity of a liquid increases with decreasing in temperature and viscosity of gas increases with increasing in temperature. 
• According to newton's law of viscosity, the shear stress is directly proportional to the velocity gradient. The constant of the proportionality is known as viscosity. Mathematically 

τ  = µ du/dy

Where µ is known as dynamic viscosity. The unit of dynamic viscosity is Pa-s or N-s/m2.

• There are two types of viscosity used in fluid mechanics one is known as dynamic viscosity (µ) and other on is known as kinematic viscosity (ν). The kinematic viscosity is ratio of the dynamic viscosity to the density of the fluid. 

ν  = µ/ρ

• The SI unit of kinematic viscosity is m2/s. 

Specific Weight:

• It is defined as weight of fluid per unit volume. 
• Mathematically, it is defined as the ratio of the weight to the volume of the fluid.  

w=  (Weight of the fluid)/(Volume of the fluid)

It can also be expressed as 

w= ρ*g

• The SI unit of the specific weight is N/m3.

Specific volume:

• It is the reciprocal of the density or we can say that it is the volume of the fluid per unit mass. 

Specific Volume=  (Volume of the fluid)/(Mass of the fluid)

• The SI unit of specific volume is m3/Kg.

Vapor Pressure:

• The pressure exerted by its vapor in phase equilibrium with its liquid at a given temperature is known as vapor pressure.  
• The vapor pressure of the fluid is increased by increasing in temperature. 
• It the liquid pressure drops below its vapor pressure at a given temperature, the liquid starts to evaporate. Petrol have more vapor pressure with respect atmospheric pressure at atmospheric temperature, so it starts to evaporate while water doesn't. 

REASON WHY THERE ARE NOT FRONT WHEEL DRIVE MOTORCYCLES

Why are there no front wheel drive motorcycles?

It should work in theory, but there are a couple things which would complicate it:

1) As a practical matter, the front wheel needs to steer as well as move up and down on the suspension.  This makes it more difficult to attach a reliable drivetrain to the front wheel, without adding unwanted mass and impeding the action of the front suspension and steering.

2) Traction.  As designed motorcycles apply the driving force at the rear wheel, and the size of the tire is chosen to minimize rear wheel spin. The front tire manages braking forces, since 70-100% of braking force comes from the front tire.  Both tires share the cornering forces.   

If you have driven a front wheel drive car aggressively, you will have noticed understeer, where applying the gas causes the car to push towards the outside of the turn, because the cornering forces plus the driving force exceed the traction limit of the tire, it slides, and the car pushes straight.  On a motorcycle this would cause a lowside crash.

But ignoring this for now:

If you were to drive the front tire, you would need to size it for engine torque, perhaps the size of a standard rear.  This would give heavier steering.  And you'd burn through fronts in half the mileage.

The rear tire, having nothing to do but cornering, could be the size of a standard front tire, or smaller.

Theoretically you could address point 1) with an electric motor, and you could make it safer with traction control.  It wouldn't be as easy, and it wouldn't have better performance, but it would certainly be unique.

Share your views in comment section !!!

VALVE AND ITS TYPE

A valve is a mechanical device that blocks a pipe either partially or completely to change the amount of fluid that passes through it. When you turn on a faucet (tap) to brush your teeth, you're opening a valve that allows pressurized water to escape from a pipe. Similarly, when you flush the toilet, you open two valves: one that allows water to escape to empty the pan and another (called a ball valve or ballcock) that admits more water into the tank ready for the next flush.

Valves regulate gases as well as liquids. If you have a gas cooktop (hob) on your stove, the controls that turn the gas up or down are valves. When you turn up the heat, you're opening a valve that allows more gas to flow in through the pipe. More gas burns with a bigger flame so you get more heat.

Valves are usually made of metal or plastic and they have several different parts. The outer part is called the seat and it often has a solid metal outer casing and a soft inner rubber or plastic seal so the valve makes a closure that's absolutely tight. The inner part of the valve, which opens and closes, is called the body and fits into the seat when the valve is closed. There's also some form of mechanism for opening and closing the valve—either a manual lever or wheel (as in a faucet or a stop cock) or an automated mechanism (as in a car engine or steam engine).

TYPES OF VALVE :-

There are  different types of valves, all have different names. The most common ones are the butterfly, cock or plug, gate, globe, needle, poppet, and spool:

• Ball: In a ball valve, a hollowed-out sphere (the ball) sits tightly inside a pipe, completely blocking the fluid flow. When you turn the handle, it makes the ball swivel through ninety degrees, allowing the fluid to flow through the middle of it.
• Butterfly: A butterfly valve is a disk that sits in the middle of a pipe and swivels sideways (to admit fluid) or upright (to block the flow completely).
• Cock or plug: In a cock or plug valve, the flow is blocked by a cone-shaped plug that moves aside when you turn a wheel or handle.
• Gate or sluice: Gate valves open and close pipes by lowering metal gates across them. Most valves of this kind are designed to be either fully open or fully closed and may not function properly when they are only part-way open. Water supply pipes use valves like this.
• Globe: Water faucets (taps) are examples of globe valves. When you turn the handle, you screw a valve upward and this allows pressurized water to flow up through a pipe and out through the spout below. Unlike a gate or sluice, a valve like this can be set to allow more or less fluid through it.
• Needle: A needle valve uses a long, sliding needle to regulate fluid flow precisely in machines like car engine carburetors and central-heating systems.
• Poppet: The valves in car engine cylinders are poppets. This type of valve is like a lid sitting on top of a pipe. Every so often, the lid lifts up to release or admit liquid or gas.
• Spool: Spool valves regulate the flow of fluid in hydraulic systems. Valves like this slide back and forward to make fluid flow in either one direction or another around a circuit of pipes.

DIFFERENCE BETWEEN DIFFUSER AND COMPRESSOR

What is the difference between a diffuser and a compressor?

Diffuser(Mechanical): A Device that is used to increase the static pressure of the fluid that passes through the system and also reducing the velocity of the fluid. Static pressure occurs when the fluid passes through the duct.

Diffuser(HVAC): A room air distribution subsystem used in both air and water cooled air conditioning systems. These are used to channelize both the conditioned and ventilated air through out the surrounding in the necessary directions. Diffuser positions are strategically decided based on the room/surrounding/system volume. They greatly reduce noise produced byt the system

Diffuser

Compressor(Mechanical): A Device that increases the pressure of the fluid by reducing the volume of the system. Similar to pumps they can be used for both compression as well as transportation.

Compressor(HVAC): A pump which draws a low pressure on the cooling side of a refrigeration cycle and compresses the refrigerant gas into the high pressure or the condensing side of the cycle.

THERMODYNAMIC SYSTEM AND SURROUNDING

When we are discussing thermodynamics, the particular item or collection of items that we’re interested in (which could be something as small as a cell, or as large as an ecosystem) is called the system, while everything that's not included in the system we’ve defined is called the surroundings.

Generalized depiction of the system (a circle), the surroundings (a square surrounding the circle), and the universe (system + surroundFor instance, if you were heating a pot of water on the stove, the system might include the stove, pot, and water, while the surroundings would be everything else: the rest of the kitchen, house, neighborhood, country, planet, galaxy, and universe. The decision of what to define as the system is arbitrary (up to the observer), and depending on what you wanted to study, you could equally well make just the water, or the entire house, part of the system. The system and the surroundings together make up the universe.

There are three types of systems in thermodynamics: open, closed, and isolated.

• An open system can exchange both energy and matter with its surroundings. The stove top example would be an open system, because heat and water vapor can be lost to the air.

• A closed system, on the other hand, can exchange only energy with its surroundings, not matter. If we put a very tightly fitting lid on the pot from the previous example, it would approximate a closed system.

Example of isolated system

• An isolated system is one that cannot exchange either matter or energy with its surroundings. A perfect isolated system is hard to come by, but an insulated drink cooler with a lid is conceptually similar to a true isolated system. The items inside can exchange energy with each other, which is why the drinks get cold and the ice melts a little, but they exchange very little energy (heat) with the outside environment.