Forums

Portable Electronic Glass Stength Tester

Started by Unknown June 26, 2013
On Thursday, June 27, 2013 6:52:17 PM UTC-4, Jeff Liebermann wrote:
> On Thu, 27 Jun 2013 10:17:59 -0700 (PDT), George Herold > > <gherold@teachspin.com> wrote: > > > > >I think I'd try some spring loaded gizmo first. > > > > The OP mentioned something about an accuracy problem. Citing my last > > rant: > > > > From IEC 61215 10.17 1st edition(1993) > > - Test apparatus as described in section 10.17 with a velocity > > repeatability of +/- 5%. > > - Instrument for velocity measurement with an accuracy of +/- 2%, no > > more than 1 m from module impact surface > > - Weighing instrument with an accuracy of +/- 2% > > - Freezer and container for production and storage of ice balls > > - Apparatus to verify ice ball diameter to within +/- 5% of > > requirement and mass within +/- 5% of requirement. > > > > >I was thinking about the ice cube on the end of a string idea, but > > >unless you've got a long string it's hard to see how you'd get > > >the panel inserted... You could release the string at some point, > > >but that strikes me as scarier than the ice-ball air cannon. > > > > Yeah, but I like your idea. However, not one string but two as in a > > traditional sling:
Sure, but not really my idea, Spehro* posted it first, so he has to file for the patent :^) Sure, but not really my idea, Spehro* posted it first, so he has to file for the patent :^) As far as some sort of accuracy... It's hail... can there be that much accuracy? Seems like yet another strike against PV. I like wind, nuclear, and we have lots of natural gas... then the other dirtier stuff that I burn in my car every day. George H.
> > <http://en.wikipedia.org/wiki/Sling_(weapon)> > > <http://www.slinging.org> > > It worked on Goliath, so a mere tempered glass window should not be a > > major challenge. I prefer 2 or 3 overhead spins because I can use a > > longer length rope, and it helps seat the projectile in the pouch, but > > vertical spins with shorter ropes should also work. To indicate the > > desired velocity, a teapot whistle, or electronic equivalent, is > > attached to the end, which signals the when to let go. Some practice > > and calibration will be required. In the event of collateral damage, > > a good insurance policy might also be useful. I suppose all this > > could be automated, in the Mythbuster style, that takes the fun out > > destructive testing. If accuracy is a problem, then several small > > hailstones could be simultaneously launched. At least one might hit > > the target panel.
Chuckle... I love pushing the limits of things. My co-wrkers always seem worried that something will break, but to me that's the point. If some mindless student can turn this knob to the limit, then we gotta make sure nothing breaks. and if it does, reduce the 'travel' of that knob.
> > > > >I've got it, set the panel on the side of the road, get your car > > >up to 50 mph with the ice ball held out the window. Trigger some > > >release mechanism at the right point so the ice-ball drops and > > >impacts the panel. Slightly more portable than than dropping > > >ice cubes from buildings. :^) > > > > Ummm... the panels are usually mounted on a rooftop. Unless there's > > an adjacent building, that is 25 meter higher, the drop test method > > isn't going to work.
OK, I can fly over in an airplane, for a price. :^) Do people really want ice cubes (or water ballons) thrown at installed PV's? George H.
> > > > However, you gave me yet another marginal idea. At 50 mph (22.4 > > meters/sec), liquid water and ice will transfer about the same amount > > of energy to the glass. No need to use a frozen ice ball proxy, when > > a small water balloon filled with non-frozen water will suffice. This > > was demonstrated by Mythbusters in the chicken cannon, and by me in > > college when I used a sling to launch water balloons. This was deemed > > a major escalation in inter-dormitory warfare and was immediately > > suppressed by the administration after I sent a fairly small water > > balloon through a non-tempered window (at about 30 meters range). > > > > > > -- > > Jeff Liebermann jeffl@cruzio.com > > 150 Felker St #D http://www.LearnByDestroying.com > > Santa Cruz CA 95060 http://802.11junk.com > > Skype: JeffLiebermann AE6KS 831-336-2558
George Herold wrote:
> > On Thursday, June 27, 2013 12:18:41 PM UTC-4, Spehro Pefhany wrote: > > On Thu, 27 Jun 2013 23:34:37 +1000, mharris@comprodex.com wrote: > > > > >Thanks for sall the mechanical suggestions. We ruled these out due to > > > > >inherent variables and aging of parts. > > > > > > > >Can anyone tell me how to build a solenoid operated plunger that will > > > > >have the necessary force? Or at least a viable starting point with > > > > >regard to circuit design. > > > > > > > > > >Mark "Hailstorm" Harris > > > > > > They're all mechanical to some degree. > > > > It remains to be seen whether the friction and other temperature etc. > > related variations in a solenoid plunger would be any better than an > > electronically calibrated spring force. > > I think I'd try some spring loaded gizmo first. > I was thinking about the ice cube on the end of a string idea, but unless you've got a long string it's hard to see how you'd get the panel inserted... You could release the string at some point, but that strikes me as scarier than the ice-ball air cannon. > > I've got it, set the panel on the side of the road, get your car up to 50 mph with the ice ball held out the window. Trigger some release mechanism at the right point so the ice-ball drops and impacts the panel. Slightly more portable than than dropping ice cubes from buildings. :^)
has anyone ever worked with 'Glass break detectors' for alarm systems? The old ones were tuned for the sound glass makes when it breaks, but some could detect the sound it makes before it shatters. The output was analog. I haven't worked with them for over 35 years, and don't remember the details.
On Thursday, 27 June 2013 23:34:37 UTC+10, mha...@comprodex.com  wrote:
> Thanks for all the mechanical suggestions. We ruled these out due to=20 > inherent variables and aging of parts. > =20 > Can anyone tell me how to build a solenoid operated plunger that will=20 > have the necessary force? Or at least a viable starting point with > regard to circuit design.
As Spehro has pointed out, a solenoid-only drive is unlikely to be able to = deliver enough energy, and - in part because a simple solenoid drive applie= s a very position-dependent force to the plunger - unlikely to deliver a pa= rticularly well-defined impact energy. As I've already said, I think you have to plan on monitoring the position -= and thus the speed and energy - of your plunger as it heads towards the gl= ass surface. You can then make an instrumented automatic centre punch, and - if necessar= y - use a magnet on your plunger with a solenoid to modify the speed of you= r plunger in the last few millimetres of travel, just before it hits the gl= ass. Because the solenoid will then only be active over a relatively small part = of the displacement, the force it exerts will be a lot more predictable, an= d close to the maximum available. There will be lots of back-emf in the sol= enoid, but you can charge up a capacitor to cope with that for the fraction= of a second that you have to deal with it. --=20 Bill Sloman, Sydney
On Thu, 27 Jun 2013 17:19:05 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>Sure, but not really my idea, Spehro* posted it first, so he has to file for the patent :^)
Nope. The new and disgusting FITF (first-to-file) means that if my soon to be patented file-o-matic patent spamming device files for the patent a few milliseconds before Sphero, then it's all mine, as in winner take all. In the past, I had to actually prove that I had the idea first. Now, all I need to do is watch the newsgroups for hints on what people are designing, and immediately file a provisional patent application. I then have about a year to amend the patent into something that will allow me to sue Sphero for infringement: <http://www.uspto.gov/patents/resources/types/provapp.jsp>
>As far as some sort of accuracy... It's hail... can there be that much accuracy?
IEC 61215 10.17 comes from a committee of interested parties, that probably have investments in companies that manufacture the required test equipment. It is therefore to their benefit to make the accuracy requirement as expensive as possible.
>Seems like yet another strike against PV. I like wind, nuclear, and we >have lots of natural gas... then the other dirtier stuff that I burn >in my car every day.
Photo voltaic is far from perfect. However, the alternatives are far worse. My favorite alternative energy scheme is solar steam power. My plan is to use solar collectors and concentrators to produce steam, which will then drive a dynamo or pump to produce electricity and move water. Possibly a buried thermal reservoir. My calculations show that the delivered energy from the roughly 1kw/sq-meter maximum solar insolation is far higher for steam than for photo voltaic. As a side benefit, the condensed water vapor can be easily purified and can be used to make coffee or tea. Like all concentrated energy devices, it is difficult to separate it from an explosive device, so some safety issues will need to be considered before mass deployment. Gasoline, which is far more concentrated and dangerous than steam is deemed safe, so I presume something can be done with steam. After that, there's the noise problem, where to get the water, how to deal with the increased humidity, and exactly how to build a government bureaucracy and research paper factory on top of the technology.
>Chuckle... I love pushing the limits of things. My co-wrkers always >seem worried that something will break, but to me that's the point.
Liebermann's 318th law of design: If it moves, it will break. This law has been generally suspected for quite some time, resulting in products with few moving parts, no controls, and no user accessible adjustments. Everything is controlled by software, which somehow is expected to make things safer. Such devices are often conceived in state machines using tables of conditions provided by the company attorneys. Unfortunately, when a state machine is presented with an undefined state, it usually does something rather disgusting. Students are therefore employed in the necessary testing, as they are known for their inability to follow instructions, their creative abuse of devices, and their attraction to dangerous devices. It also helps that they're also disposable.
>If some mindless student can turn this knob to the limit, then we >gotta make sure nothing breaks. >and if it does, reduce the 'travel' of that knob.
I have a theory that safety devices cause more accidents than they prevent. Such safety devices make workers and students feel that they are being protected by the safety device, resulting a new classes of imaginative and creative ways to produce an accidental injury. A good indication of the failure of safety devices to prevent accidents and the associated litigation are the voluminous "wholesale repudiation of responsibility" documents and imaginative warning labels found on almost all current products more complicated than a pencil. I wouldn't worry about protecting students from themselves. Instead, I suggest you concentrate on the documentation that nobody reads and the warning labels, as making a product safe is a futile exercise.
>OK, I can fly over in an airplane, for a price. :^) >Do people really want ice cubes (or water ballons) thrown at installed PV's?
I live in a forest, so PV solar is not very common. I do have friends in the flatlands, that have PV installations including a former lady friend. My interest in the monitoring and data collection of her system has somehow entitled me to scrub and clean the bird droppings, tree debris, dirt, and grease from the panels several times per year. Cleaning the panels is easy. Cleaning out the critters that have moved in under the solar panels is not so easy. The tempered glass appears to be strong enough to withstand a nuclear blast, and will certainly survive an ice cube drop. A quick search with Google excavates little concern over hail stone damage. However, I suspect that installers, dealers, and insurance underwriters might want to know, which may have inspired this project. On the other hand, using an airplane for testing has other risks that should be considered: <https://www.google.com/search?q=falling+airplane+parts&tbm=isch> as well as the aircraft adding some errors to the ice fall: <http://en.wikipedia.org/wiki/Blue_ice_(aircraft)> There are also falls of fish, frogs, snakes, etc: <http://en.wikipedia.org/wiki/Raining_animals> With about a 1500ft LSALT over populated areas, accuracy will certainly be a problem: <http://en.wikipedia.org/wiki/Lowest_safe_altitude> Perhaps a fin guided and gyro stabilized ice ball might be worth designing. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On Thu, 27 Jun 2013 20:21:40 -0400, the renowned "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

> > > has anyone ever worked with 'Glass break detectors' for alarm >systems? The old ones were tuned for the sound glass makes when it >breaks, but some could detect the sound it makes before it shatters. >The output was analog. I haven't worked with them for over 35 years, and >don't remember the details.
I just remember the ones that were made with foil.. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
On Thu, 27 Jun 2013 20:21:40 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

> has anyone ever worked with 'Glass break detectors' for alarm >systems?
Not worked with, but I do have one on my office windows. However, I didn't have a sensor on the front door. So... <http://www.11junk.com/jeffl/pics/office/slides/broken-glass.html> The alarm did NOT trigger, so I have no clue if the devices actually work.
>The old ones were tuned for the sound glass makes when it >breaks, but some could detect the sound it makes before it shatters. >The output was analog. I haven't worked with them for over 35 years, and >don't remember the details.
Yeah, there are several methods. I found this which might help: <http://www.best-microcontroller-projects.com/glass-break-detector.html> I didn't see anything on predicting if the glass was going to break. I suspect that the major interest is not so much if the tempered glass was broken, but rather whether the solar cells behind the tempered glass sustained any damage. Thin film and amorphous are fairly flexible, but monocrystalline and polycrystalline will break if bent even slightly. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
<mharris@comprodex.com> wrote:
> Thanks for sall the mechanical suggestions. We ruled these out due to > inherent variables and aging of parts. > > Can anyone tell me how to build a solenoid operated plunger that will > have the necessary force? Or at least a viable starting point with > regard to circuit design. > > Mark "Hailstorm" Harris
As I see it, your problem (and the device you want) are inherently mechanical. The electronics you seek are mainly a wrapper around the mechanical bits to calibrate it. So perhaps rethink and repose the question in that manner.
On Thu, 27 Jun 2013 18:27:55 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
> >The tempered glass appears to be strong enough to withstand a nuclear >blast, and will certainly survive an ice cube drop. A quick search >with Google excavates little concern over hail stone damage. However, >I suspect that installers, dealers, and insurance underwriters might >want to know, which may have inspired this project. >
I have a friend who lives in a golf course community. He found out (to around $8K in damage!) that solar panels can not stand up to a well driven golf ball! He put up screens about a foot over his panels to protect them from the golf balls. Would probably work for hail as well. Of course, it does cut back on his production a little bit... Charlie
On 6/27/2013 9:48 AM, Syd Rumpo wrote:
> On 27/06/2013 17:18, Spehro Pefhany wrote: >> On Thu, 27 Jun 2013 23:34:37 +1000, mharris@comprodex.com wrote: >> >>> >>> Thanks for sall the mechanical suggestions. We ruled these out due to >>> inherent variables and aging of parts. >>> >>> Can anyone tell me how to build a solenoid operated plunger that will >>> have the necessary force? Or at least a viable starting point with >>> regard to circuit design. >>> >>> Mark "Hailstorm" Harris >> >> >> They're all mechanical to some degree. >> >> It remains to be seen whether the friction and other temperature etc. >> related variations in a solenoid plunger would be any better than an >> electronically calibrated spring force. >> >> Regardless of how you drive them, solenoids provide a very nonlinear >> force with plunger position.. so they're actually not very well suited >> to your application. The more efficent ones (with a closed magnetic >> circuit when they're actuated) are much worse. Some of the temperature >> related variation could be eliminated with a constant current type >> drive, but I doubt that's your biggest problem with that approach. >> >> Maybe you could fling a mass around with a motor. Or pump up a >> relatively large reservoir with air to a calibrated pressure and use >> an air cylinder. Or if cost is not a concern and you're stuck on the >> solenoid-ish idea, consider a linear motor*. > > <snip> > > A 'voice coil actuator' would be better than a solenoid. I know little > of these but Google has lotsa hits... > > http://www.orlin.co.uk/voice-coil.htm is one such. > > Cheers
Do it pneumatically. -- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com
In article <ck3ns85un3gj03cd8k22gpjt3kf6m76fl2@4ax.com>,
<mharris@comprodex.com> wrote:

> I would like to inquire regarding circuit design options for a > custom-made testing device. > > It is intended to test the breaking strength of glass sheet on solar > panels in the field. Hence, it needs to be portable, running off > something like two 3.7V Li-ion batteries. > > The concept is to use a solenoid-type plunger that is activated one > time by a push button. This strikes the glass with a predetermined > breaking strength to check for durability against hail damage, etc. > > I suspect something like a storage cap would be required, but would > appreciate some suggestions on how best to proceed. I repeat, the > device needs to be small and battery powered (for safety).
Why so complicated? Just drop a ball bearing a specified distance onto the glass sample, just like the test for the breakability of industrial safety eyeglass lenses. What I recall for industrial lenses is that the test used a 16-ounce steel ball dropped one foot. I had an old pair of glasses with industrial tempered glass lenses, so I took a lens out, put it in a horizontal plank, outward side up, and dropped a 16-ounce hammer head on it. The lens survived. So I kept going higher till it broke; don't recall the final height, but it was a lot more than 12". So that's why my father always bought industrial lenses for me. For all eyeglass lenses (non-industrial): "The regulation at 21 CFR 801.410(d)(2) describes the exact procedure for the impact test (See Appendix A). The regulation states, &sup3;In the impact test, a 5/8-inch steel ball weighing approximately 0.56 ounce is dropped from a height of 50 inches upon the horizontal upper surface of the lens. The ball shall strike within a 5/8 inch diameter circle located at the geometric center of the lens. The ball may be guided but not restricted in its fall by being dropped through a tube extending to within approximately 4 inches of the lens. To pass the test, the lens must not fracture&Scaron;.&sup2; Joe Gwinn