BY: NANDAN HEGDEBY: NANDAN HEGDE

INTRODUCING SMART SAFETY INTRODUCING SMART SAFETY DEVICES DEVICES

1. A seat belt, sometimes called a safety belt, is a safety harness designed to secure the occupant of a vehicle against harmful movement that may result from a collision or a sudden stop

2. Seat belts are intended to reduce injuries by stopping the wearer from hitting hard interior elements of the vehicle, or other passengers (the so-called second impact), are in the correct position for the airbag to deploy and prevent the passenger from being thrown from the vehicle. Seat belts also absorb energy by being designed to stretch during an impact, so that there is less speed differential between the passenger's body and their vehicle interior, and also to spread the loading of impact on the passengers body.

Well, as we all know ……….

Lap seat belt (or "two points") in an aircraft

Three points seatbelt in a car. The three points belt is the standard seat belt for road cars.

Five points harness in a racing car.

Types Of Seat Belts

Most seat belts are equipped with locking mechanisms (or inertia reels) that tighten the belt when pulled fast

but do not tighten when pulled slowly. This is implemented with a centrifugal clutch, which engages as the reel spins quickly. Alternatively, this function may be secured by a weighted pendulum or ball bearing: when these are deflected by deceleration or roll-over they lock

into pawls on the reel.Seat Belt

uncovered Inertial Reel

Technology

Seatbelts in many newer vehicles are also equipped with "pretensioners" and/or "Webclamps".

Pretensioners preemptively tighten the belt to prevent the occupant from jerking forward in a crash. Mercedes-Benz first introduced pretensioners on the 1981 S-Class. In the event of a crash, a pretensioner will tighten the belt almost instantaneously. This reduces the motion of the occupant in a violent crash. Like airbags, pretensioners are triggered by sensors in the car's body, and most pretensioners use explosively expanding gas to drive a piston that retracts the belt. Pretensioners also lower the risk of "submarining", which is when a passenger slides forward under a loosely worn seat belt. An alternative approach being looked at by major car companies is the CG-Lock technology whereby the occupant is held in position via the lap belt in order to prevent the passenger from coming out of position in the event of a crash.

Pretensioners and webclamps

Inflatable seat belts. At a glance, that doesn't seem like such a bad idea after all, particularly for those rear seat passengers who aren't blessed with two huge bags or air right in front of their chest. The top brass at Ford feel pretty much the same way, as the outfit has just announced that these very devices will be making their debut in the next-generation Ford Explorer before rolling out across the fleet. Of course, Lexus is also planning to shove these into its ultra-luxurious LFA (which will probably make a grand total of 14 wealthy owners feel really, really safe), but it's tough to tell which vehicle will hit the showroom first.

Ford's inflatable seat belts headed to Explorer in 2010

AIRBAGS Airbags are inflating elements used to safeguard a

person from accidental impact collisions.

The goal of an airbag is to slow the passenger's forward motion as evenly as possible in a fraction of a second.

It is one of the best passive safety devices which are used in contrast to the seat belts.

Immediately after full inflation, the airbag deflates. Hence Airbag is considered as the best restraint safety device.

HISTORY OF HISTORY OF AIRBAGSAIRBAGS

An American inventor, John W. Hetrick, a retired An American inventor, John W. Hetrick, a retired industrial engineer, designed the original safety industrial engineer, designed the original safety cushion for automotive use in 1952 at his kitchen cushion for automotive use in 1952 at his kitchen table. table.

Airbags for passenger cars were introduced in the Airbags for passenger cars were introduced in the United States in the mid-1970s, when Seat Belts United States in the mid-1970s, when Seat Belts usage rates in the country were quite low.’usage rates in the country were quite low.’

Ford’ built an experimental fleet of cars with Ford’ built an experimental fleet of cars with airbags in 1971, followed by ‘General Motors’ in airbags in 1971, followed by ‘General Motors’ in 1973 on ‘Chevrolet’ vehicles. 1973 on ‘Chevrolet’ vehicles.

Technology Technology Behind AirBagsBehind AirBags

According to Law of Inertia” A body persists in a state of According to Law of Inertia” A body persists in a state of rest or of uniform motion unless acted upon by an rest or of uniform motion unless acted upon by an external force". Here we consider Impact force as an external force". Here we consider Impact force as an external agent which causes sudden deceleration of the external agent which causes sudden deceleration of the vehicle.vehicle.

We know that moving objects have We know that moving objects have momentummomentum (the (the product of the mass and the velocity of an object). Cars product of the mass and the velocity of an object). Cars consist of several loose objects in the car and, of course, consist of several loose objects in the car and, of course, passengers. If these objects are not restrained, they will passengers. If these objects are not restrained, they will continue moving at whatever speed the car is traveling continue moving at whatever speed the car is traveling at, even if the car is stopped by a collision. at, even if the car is stopped by a collision.

Stopping an object's momentum requires force acting Stopping an object's momentum requires force acting over a period of time. When a car crashes, the force over a period of time. When a car crashes, the force required to stop an object is very great because the car's required to stop an object is very great because the car's momentum has changed instantly while the passengers' momentum has changed instantly while the passengers' has not -- there is not much time to work with. has not -- there is not much time to work with.

.. Air bags do not just cushion your body in the Air bags do not just cushion your body in the

event of an impact, but they also spread the event of an impact, but they also spread the impact over a larger area. By doing this, the impact over a larger area. By doing this, the force is not all concentrated in one small area force is not all concentrated in one small area of your body. This in turn will cause the of your body. This in turn will cause the seriousness your injuries to be reduced because seriousness your injuries to be reduced because the force you feel is spread out.the force you feel is spread out.

AIRBAGS FAMILYAIRBAGS FAMILY

3 Main 3 Main Components:Components: 1) 1) Airbag moduleAirbag module

2) 2) Diagnostic UnitDiagnostic Unit

3) Crash 3) Crash sensorssensors

Airbag Module:Airbag Module:Contains both inflator unit and light-weight fabric Contains both inflator unit and light-weight fabric airbag and is located either inside: 1) Steering airbag and is located either inside: 1) Steering wheel hub 2) Above glove Compartment 3) Near wheel hub 2) Above glove Compartment 3) Near side compartment (as separate/combined side compartment (as separate/combined head/side/window-curtain airbag).head/side/window-curtain airbag).

Diagnostic Unit:Diagnostic Unit: 1)Enables inflator unit and sensors when vehicle 1)Enables inflator unit and sensors when vehicle

is turned on, performs self check.is turned on, performs self check.2)Constantly monitors airbag readiness and 2)Constantly monitors airbag readiness and indicates malfunctioning through an indicator on indicates malfunctioning through an indicator on dashboard.dashboard.

Crash Sensors:Crash Sensors:1)Several crash sensors located in the front of 1)Several crash sensors located in the front of vehicle and in the passenger compartmentvehicle and in the passenger compartment2)Each senses the sudden deceleration or impact in 2)Each senses the sudden deceleration or impact in the event of a crash and flips a mechanical switch the event of a crash and flips a mechanical switch to indicate a crash. to indicate a crash.

WORKING OF AIRBAGWORKING OF AIRBAG ACU consists of crash sensors which receives threshold ACU consists of crash sensors which receives threshold

values. The signals from the various sensors are fed into values. The signals from the various sensors are fed into the Airbag control unit, which determines from them the Airbag control unit, which determines from them the angle of impact, the severity, or force of the crash, the angle of impact, the severity, or force of the crash, along with other variables.along with other variables.

When the requisite 'threshold' has been reached or When the requisite 'threshold' has been reached or exceeded, the airbag control unit will activate one or exceeded, the airbag control unit will activate one or more Pyrotechnic devices.more Pyrotechnic devices.

Pyrotechnics is the science of materials capable of Pyrotechnics is the science of materials capable of undergoing self-contained and self-sustained undergoing self-contained and self-sustained exothermic chemical reactions for the production of exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound.heat, light, gas, smoke and/or sound.

Crash SensorCrash Sensor

Who inflates Airbag ?Who inflates Airbag ? IT IS SODIUM AZIDEIT IS SODIUM AZIDE

Sodium azideSodium azide is the inorganic salt with is the inorganic salt with the formula NaN3. This colorless azide the formula NaN3. This colorless azide salt is the gas-forming component in salt is the gas-forming component in many car airbag systems.many car airbag systems.

The following reactions take place to liberate nitrogen The following reactions take place to liberate nitrogen gas which in turn inflates Airbag:gas which in turn inflates Airbag:

2NaN3 2NaN3 2Na + 3N2 2Na + 3N2 10Na + 2KNO3 10Na + 2KNO3 K2O + 5Na2O+ N2 K2O + 5Na2O+ N2

This nitrogen produced inflates the Airbag. This nitrogen produced inflates the Airbag.

After Inflation Nylon fabric Bag contains small After Inflation Nylon fabric Bag contains small pores through which the nitrogen gas escapes out pores through which the nitrogen gas escapes out to the atmosphere.to the atmosphere.

Failure to wear a seat belt contributes to more fatalities than any other single traffic safety-Failure to wear a seat belt contributes to more fatalities than any other single traffic safety-related behavior. related behavior. 63% of people killed in accidents are not wearing seat belts. Wearing a seat are not wearing seat belts. Wearing a seat belt use is still the single most effective thing we can do to save lives and reduce injuries.belt use is still the single most effective thing we can do to save lives and reduce injuries.

Data suggests that education alone is not doing the job with young people, especially males Data suggests that education alone is not doing the job with young people, especially males ages 16 to 25 the age group least likely to buckle up. They simply do not believe they will be ages 16 to 25 the age group least likely to buckle up. They simply do not believe they will be injured or killed. Yet they are the nation's highest-risk drivers, with more drunk driving, more injured or killed. Yet they are the nation's highest-risk drivers, with more drunk driving, more speeding, and more crashes. Neither education nor fear of injury or death is strong enough to speeding, and more crashes. Neither education nor fear of injury or death is strong enough to motivate this tough-to-reach group.motivate this tough-to-reach group.

The Seat belts are the most effective safety devices in vehicles today, estimated to save 9,500 The Seat belts are the most effective safety devices in vehicles today, estimated to save 9,500 lives each year. And also the National Highway Traffic Safety Administration (NHTSA) has lives each year. And also the National Highway Traffic Safety Administration (NHTSA) has estimated that air bags have saved almost 1,500 lives, with an estimated 569 lives saved in estimated that air bags have saved almost 1,500 lives, with an estimated 569 lives saved in 1995 alone.1995 alone.

Nowadays a fantastic concept has been introduced in Airbags that is in addition to the crash Nowadays a fantastic concept has been introduced in Airbags that is in addition to the crash sensors one more sensor is used which determines whether the person is out of position(OOP) sensors one more sensor is used which determines whether the person is out of position(OOP) or not and other variables. or not and other variables.

The auto racing which is considered as a most dangerous sport is now safe by the use of The auto racing which is considered as a most dangerous sport is now safe by the use of advanced smart safety devices like advanced smart safety devices like Crumple zones and AirbagsCrumple zones and Airbags and have greatly reduced crash and have greatly reduced crash impact forces on drivers and has saved the life of numerous people. Fatality rates have been impact forces on drivers and has saved the life of numerous people. Fatality rates have been drastically reduced. Air bags have been and continue to be an effective, life-saving technology.drastically reduced. Air bags have been and continue to be an effective, life-saving technology.

Nowadays because of increased traffic, the auto safety has become major problem. Of course Nowadays because of increased traffic, the auto safety has become major problem. Of course keeping people safe in auto accidents is not a simple job. But by the implementation of Smart keeping people safe in auto accidents is not a simple job. But by the implementation of Smart Safety Devices the damage that is caused to a person inside the car or vehicle has been Safety Devices the damage that is caused to a person inside the car or vehicle has been reduced drastically. reduced drastically.

Conclusion