Thoughts on 2015-16 car design.

[shp4man]

Starting in about 2006, the rise of the machines became clear. Automotive parts and systems were in most cases no longer designed by humans, but by machines with input from humans. I know,  I have to work on these alien creations every day. It's not easy with the usually unclear, multinational picture based service manuals they have these days.

Maybe the factory is just pissed, because they know we can't be replaced by  an offshore slave labor worker

Oh well, most of  us are old farts. God only knows who they'll replace us with when we're gone.

[ifcar]

What sorts of things have changed in the design?

[MX793]

As design tools have become more sophisticated (and no, cars are not designed "by machines", they are designed using machines), tolerances and packaging can be designed ever tighter.  They are increasingly putting more stuff in the same sized bag with less and less clearance space to actually be able to work on the vehicles when stuff breaks or wears out.  I'd argue they focus more on designing for easy assembly than designing for easy repair.

[Eye of the Tiger]

More retro. It is possible to exactly replicate a classic car's outward appearance using molded plastic on a unibody chassis. The 2017 Model A Ford with a 400 hp Ecoboost I-3, AWD, 40mpg highway, and a five star safety rating, coming soon.

[shp4man]

As design tools have become more sophisticated (and no, cars are not designed "by machines", they are designed using machines), tolerances and packaging can be designed ever tighter.  They are increasingly putting more stuff in the same sized bag with less and less clearance space to actually be able to work on the vehicles when stuff breaks or wears out.  I'd argue they focus more on designing for easy assembly than designing for easy repair.

Human error is now added to software bugs, notice all the stupid recalls from all the manufacturers?

[MX793]

Software bugs are human error.  Upside is that software is generally easy to update once the coders have fixed the error in the code.  But it is an additional layer of complexity beyond the physical design of the vehicle.

[Eye of the Tiger]

Human error is now added to software bugs, notice all the stupid recalls from all the manufacturers?

Chrysler-Fiat.... Omg why do people buy that shit?

[Rupert]

As a guy who sometimes works on his cars, I really appreciate the 944's relative easy access and standardization. As a guy who likes good cars cheaper, I like the modern way of putting together a car (for the most part). Cars in the last five years are just about universally better than cars from ten years ago.

[shp4man]

Software bugs are human error.  Upside is that software is generally easy to update once the coders have fixed the error in the code.  But it is an additional layer of complexity beyond the physical design of the vehicle.

Since CAD programs have no inherent common sense and are designed by programmers with no real experience in "hold it in your hand" components, and most mechanical engineers couldn't change a flat tire if their lives depended on it, you get the result of literally millions of recalled vehicles for poorly designed parts. Maybe the manufacturers need to re-hire some of the old iron pants engineers from back in the day to show them a few "analog" skills.

[giant_mtb]

So, before CAD, parts were all perfect and there were no defects or recalls?  I also feel like we are very recall-happy, too. If it ain't perfect, there's a lawsuit or a recall. I just randomly got a check from some Sylvania lighting settlement for $12 for a vehicle I don't even own anymore. Not a clue what it's about. But recall!

[MX793]

Since CAD programs have no inherent common sense and are designed by programmers with no real experience in "hold it in your hand" components, and most mechanical engineers couldn't change a flat tire if their lives depended on it, you get the result of literally millions of recalled vehicles for poorly designed parts. Maybe the manufacturers need to re-hire some of the old iron pants engineers from back in the day to show them a few "analog" skills.

CAD jockies are not programmers.  They are engineers and designers.  Programmers make the rendering software, but it's engineers and designers creating the CAD models.  Hand drawings have no common sense either.  I can draw things by hand that are every bit as impossible to build as I can create in CAD. 

Auto companies do pretty extensive prototyping and preproduction builds.  By the time the first production vehicles roll off the line, they would have built at least a hundred prototypes and preproduction examples through the course of development.

[shp4man]

CAD jockies are not programmers.  They are engineers and designers.  Programmers make the rendering software, but it's engineers and designers creating the CAD models.  Hand drawings have no common sense either.  I can draw things by hand that are every bit as impossible to build as I can create in CAD. 

Auto companies do pretty extensive prototyping and preproduction builds.  By the time the first production vehicles roll off the line, they would have built at least a hundred prototypes and preproduction examples through the course of development.

CAD jockies are not programmers, but the people that design the programs are. I would imagine they (the programmers) loaded the things with numbers fed to them by engineering schools to "make the job easier". What could possibly go wrong? 
What I meant by "common sense" is the ability to see a potential failure at some point down the road that only a human could see in the design.  And therein lies the problem.

Add in the questionable quality of offshore parts manufacturing and BAM!, it's recall/ high failure rate time!

[MX793]

You obviously have never used a CAD program.  CAD is just a means of drawing things.  At best it can tell you if parts are lined up and will mate together, nominally.  It does not predict failure any more than a hand-drawn paper drawing can.

[giant_mtb]

You obviously have never used a CAD program.  CAD is just a means of drawing things.  At best it can tell you if parts are lined up and will mate together, nominally.  It does not predict failure any more than a hand-drawn paper drawing can.

But FEA. 

[shp4man]

You obviously have never used a CAD program.  CAD is just a means of drawing things.  At best it can tell you if parts are lined up and will mate together, nominally.  It does not predict failure any more than a hand-drawn paper drawing can.

So there are no calculations as to the needed bracing or strength of a given design built into the program or programs used to design auto parts? I find that very difficult to believe. Are you an automotive/or other engineer?   

[MX793]

But FEA. 

Which is just a calculator.  It's only as good as the user.  Garbage in begets garbage out.  FEA is actually just a mathematical method.  It can be done with paper and pencil, though I wouldn't recommend trying that with anything but the most simplistic of models (for which you could just use traditional stress calculations for true solutions).

If anything, FEA permits tighter FoS, reducing the amount of over design and associated waste.  But, when margins are smaller, margin for error also shrinks.

[giant_mtb]

So there are no calculations as to the needed bracing or strength of a given design built into the program or programs used to design auto parts? I find that very difficult to believe. Are you an automotive/or other engineer?   

Old video (2009), but you can see here that modern CAD programs allow for analysis in the box for determining strength, weak points, material strength, etc.  I think it's pretty cool.  Obviously, it can't be taken as 100% fact and must be tested in the real world since there are a million other factors to consider, but stuff like in-the-box FEA allows designers to at least see the stresses parts will be under so they can adjust their designs accordingly.

https://www.youtube.com/watch?v=1f-BnJnWpUY

[MX793]

So there are no calculations as to the needed bracing or strength of a given design built into the program or programs used to design auto parts? I find that very difficult to believe. Are you an automotive/or other engineer?   

I am an engineer.  There are programs to calculate stresses.  But as with any calculator, garbage in begets garbage out.

[giant_mtb]

Which is just a calculator.  It's only as good as the user.  Garbage in begets garbage out.  FEA is actually just a mathematical method.  It can be done with paper and pencil, though I wouldn't recommend trying that with anything but the most simplistic of models (for which you could just use traditional stress calculations for true solutions).

If anything, FEA permits tighter FoS, reducing the amount of over design and associated waste.  But, when margins are smaller, margin for error also shrinks.

Good point.  How much does FEA get used in "the real world?"  I remember my housemates (all engineers) had many projects where they had to do FEA on their designs.  Dunno how that translates to actual engineering.

[MX793]

Good point.  How much does FEA get used in "the real world?"  I remember my housemates (all engineers) had many projects where they had to do FEA on their designs.  Dunno how that translates to actual engineering.

I use it on most every structural piece I design save for very basic parts for which stresses can be calculated relatively easily "by hand".  But I don't use the modules built into CAD programs like ProE or Inventor.  I import into a dedicated FEA program like ANSYS.

[shp4man]

Recalls will continue until common sense is restored.      For me, it's job security. Do/will they actually fire people for designing a part that causes huge costly problems? I always wondered about that.

[MX793]

I'd be curious to see an example of a recall due to a lack of common sense.  Generally your "lack of common sense" types of design flaws get hashed out within the first few prototypes or preproduction runs.

There will still be lack of common sense aspects that may make a vehicle a PITA to work on, but that type of flaw doesn't affect reliability or safety and doesn't prompt a recall.

[shp4man]

I'd be curious to see an example of a recall due to a lack of common sense.  Generally your "lack of common sense" types of design flaws get hashed out within the first few prototypes or preproduction runs.

There will still be lack of common sense aspects that may make a vehicle a PITA to work on, but that type of flaw doesn't affect reliability or safety and doesn't prompt a recall.

I have held in my hand some of the poorly designed garbage recalled by the manufacturers, which upon inspection, a freaking Pep Boys mechanic could see the problem with. I know that's not what you want to hear, but it's the reality.

[MX793]

I'm legitimately curious of specific examples.  I've spent several years in the role of production support, which entails following designs from paper into production and dealing with and correcting design flaws that made it into production.

[shp4man]

I'm legitimately curious of specific examples.  I've spent several years in the role of production support, which entails following designs from paper into production and dealing with and correcting design flaws that made it into production.

Ford 5.4L 3 valve V8's have an unusual spark plug design. Nobody considered carbon buildup on the lower surface of the plug, or it wasn't factored into the design program. So, sometimes they break when attempting removal. People get pissed when they have to pay big bucks just to change spark plugs.


There are literally thousands of issues like this, from all the manufacturers. You already know about the Takata air bags, I assume.

[giant_mtb]

I'm legitimately curious of specific examples.

Same!

[MX793]

The hassle of changing plugs on F150s is pretty well known.  Poor design for maintainability, but I'm not aware of any recalls associated with them.

[Eye of the Tiger]

My work F150 runs like shit and gets 11mpg highway. There is nothing wrong with it, though.

[GoCougs]

Since CAD programs have no inherent common sense and are designed by programmers with no real experience in "hold it in your hand" components, and most mechanical engineers couldn't change a flat tire if their lives depended on it, you get the result of literally millions of recalled vehicles for poorly designed parts. Maybe the manufacturers need to re-hire some of the old iron pants engineers from back in the day to show them a few "analog" skills.

Engineers who use CAD are almost always very hands on, and in any mature corporation that designs stuff prototyping (= hands on) is a lot of how they design things.

Automakers know perfectly well how well (or not) how good their designs are when it comes to repair. Thing is, by and large, they don't care. The easier a car is designed to be repaired the more compromised the design.

[AutobahnSHO]

weight, color, gas mpgeez, size, style, price

Buyers do not care about repairability