Auto Testing

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When you hear the words new car testing, what probably flashes to mind are dramatic videos of cars deliberately smashed against walls in a closed facility with a number of dummies inside. In reality, this is only one of the many tests cars go through before entering the market.

Post premarket auto tests are carried out in “the real world” to see how the car, including its components (paintwork, engine, etc) cope with the vigorous conditions; mud, fording streams, icy conditions and so on.

car-1242080_1920The actual number of tests that a manufacturer takes a car on is a closely guarded secret, but it is known that they use places like Death Valley or a test track in the mountains of Germany in order to see how the car operates. The testers are interested in how the car accelerates and, perhaps more importantly to us as drivers, how it brakes. Generally, they are looking for how the car handles on these extreme roads and this driving routine.

Driving smoothness in what most people might feel are unsmooth conditions is important. Although it would be impossible to remove all the bumps and jolts it is up to the designers the minimize discomfort.

Comfort is another aspect that people tend to need to think about. If the front seats or the back seats do not feel right some redesigning might be needed. Then there’s the problem of leaks, either air leaks or fluid leaks might need to be looked at. Is there a likelihood of something further along the line? Your prototype is your opportunity to address problems before they get truly expensive, which is when it’s gone into production.

Although unfamiliar to most of us, the industry refers to this as “rig and component level testing.” Think of the rig as another name for the chassis or body and the components as everything else. More precisely, rig testing works out exactly how durable and sensitive the chassis is to certain stimuli, and component testing focuses on individual elements and how they work together.

Some tests require the car to be built but others can be accomplished through computer simulations. Jaguar, for instance, uses computer simulation as a good way to save money. Why build a car that will be considered unsafe? Many people have heard of Computer Aided Design or CAD but the car industry is more reliant on CAE or Computer Aided Engineering. Simulation is hardly a new use of computers but as technology increases the number of virtual tests also increases.

Perhaps the single most important car feature, after safety, is fuel economy. Despite all the projections about miles per gallon, someone has to actually drive the car far enough to establish the actual number. Until recently, cars haven’t been very efficient in this respect, but car buyers are starting demand better efficiency even in luxury sedans and trucks. The need to save energy and fuel prices changes things.

There is so much testing involved in automobile manufacturing that is a wonder that any car ever goes into production at all. Perhaps more startling is the number of high profile recalls of cars in recent years given the rigorous testing designed to make the cars safer. Still, with all the money involved, and all the possibilities of what could go wrong, testing is an important step in the process.

 

The Sound of Silence

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This post was written by our overseas contributor, Paul. He’s from the U.K. so I’ve provided some interpretations for those of us in the U.S. Just having a go at you, Paul.

  • Indicators = Turn Signal
  • Windscreen = Windshield

The Sound of Silence

When you use a car all day every day you begin to recognize its individual sounds. The sound of the ignition starting up, the sound of the windscreen wipers, the sound of the indicators. When you hear a noise you don’t recognize you instantly get the feeling something is wrong. But stepping back a bit, why do cars make any noise at all?

We assume cars make a noise for the same reason jet airplanes make a noise–big engines are noisy. It’s all do with their mechanical nature. Despite the fact that many components in a car have become computerized, it is still really a mechanical object.

Internal combustion engines suck a fuel-air mixture into two or more chambers, and POW, there’s a series of explosion. Tiny explosions, sure, but it’s going to make a noise. That sound would actually be quite a bit louder except for the exhaust system which channels the exhaust and sound back along the bottom of your vehicle to dissipate it before dispersing it out to the world. Along the way, it goes through a muffler designed specifically to reduce the sound. (Except, of course, for the jerks that live behind my house, who’ve never heard of a muffler.)

But some noises are harder to place than others, the sound of rubber tires on the road is something we all recognize, but why do objects like the windscreen wipers and the indicators make the noise that they do?

Although they are performing mechanical functions, the circuitry performing these actions helps create a noise. In the case of the indicators, what we hear as a click is a circuit whose function is to cause the indicators to flash. This might not make much sense, as we encounter lights all day long which don’t make a noise, apart from some humming, but because the indicator is needed to flash, there needs to be a certain type of circuit here.

Why does a faster car make more noise? Well, when a car is accelerating its exhaust has to work harder. It’s quite complicated what is going on, but in layman’s terms, it is a mixture of axles, pistons, and transmissions which need to work harder in order to increase the speed. More work means more energy, which we hear as sound. This is also why the engine is more vocal when you start the car up, especially on cold days.

We tend to be more suspicious of the less mechanical noises, the thumps and the twangs, such as may happen when the tires rub against metal or something in the trunk hits the side of the car. It might be part of our survival instinct; no one wants to drive a vehicle which is a death trap. If there’s a problem it should be fixed. It doesn’t mean that everybody takes notices of these sounds, but many drivers feel it is part of maintaining a car properly.

One fun fact, new cars often come with long mileage tires which have very hard rubber. So they will make a lot more sound inside your car than the ones you put on later.

So what about a silent engine? Well, that can only be achieved by an electric car but they provide their own problems. Pedestrians are used to cars making a noise, so when they don’t hear a car they feel that no car is there. It makes sense, therefore, to add sound to the noise of the electric car. The only problem is that a selling point of an electric car was its smooth movement, its lack of noise. So you remove this if you add a different noise when the car is in motion.

For good or bad it seems that cars will be noisy for quite a time yet.