Forums

Portable Electronic Glass Stength Tester

Started by Unknown June 26, 2013
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).

Mark Harris
<mharris@comprodex.com> wrote in message 
news:ck3ns85un3gj03cd8k22gpjt3kf6m76fl2@4ax.com...
> > 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). > > Mark Harris
Make it realistic. Use a pump pellet gun.
On Wed, 26 Jun 2013 21:47:32 -0400, "tm" <No_one_home@white-house.gov>
wrote:

> ><mharris@comprodex.com> wrote in message >news:ck3ns85un3gj03cd8k22gpjt3kf6m76fl2@4ax.com... >> >> 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). >> >> Mark Harris > >Make it realistic. Use a pump pellet gun. >
Actually UL1703 uses a 6.78 joule impact ;) Cheers
On Thu, 27 Jun 2013 11:10:33 +1000, mharris@comprodex.com wrote:

>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.
Find a low friction ramp, and a method of supporting it perpendicular to the panel. Roll a large steel bearing down the ramp. The energy transferred will be controlled by the distance the ball is started up the ramp, and the angle of the ramp. Some math will be required. This is similar to the Charpy and Izod impact tests. No electronics required. Sounds like a job for an air canon. Mythbusters did something like that when testing the resistance of a Cessna 150 wind screen to impacts by frozen chickens. A scaled down version should work. Presumably, the hail stones will hit terminal velocity (about 200 mph) depending on its wind resistance, which will probably destroy any solar panel. Safety might be a problem. However, if you're "only" interested in launching hail stones at the solar panel: <http://www.renewableenergyworld.com/rea/blog/post/2010/08/the-strength-and-durability-of-solar-panels> "This type of glass is designed to withstand a direct vertical impact of hail up to 1 inch in diameter, traveling at 50 miles per hour." With the 1" hailstone and 50 mph. volume = 4/3 * Pi * r^2 = 1.33 * 3.14 * 0.5^2 = 1.04 in^3 which has a mass of: 1.04 * 0.036127 lbs/in^3 = 0.038 lbs = 0.0172 kg 50 mph = 22.4 meters/sec At 50 mph, the energy delivered is: Energy = 0.5 * mass * velocity^2 = 0.5 * 0.0172 * 22.4^2 = 4.3 joules That can be done with a solenoid gun or an air or spring power launcher. -- 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 Thursday, 27 June 2013 12:03:44 UTC+10, Martin Riddle  wrote:
> On Wed, 26 Jun 2013 21:47:32 -0400, "tm" <No_one_home@white-house.gov>=20 > wrote:=20 > ><mharris@comprodex.com> wrote in message=20 > >news:ck3ns85un3gj03cd8k22gpjt3kf6m76fl2@4ax.com...=20 > >> > >> I would like to inquire regarding circuit design options for a > >> custom-made testing device.=20 > >> > >> 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=20 > >> 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). > > > >Make it realistic. Use a pump pellet gun. > =20 > Actually UL1703 uses a 6.78 joule impact ;)
You are going to want to monitor the position of the plunger in real time. = It's easy enough to determine the mass of the plungers, and if you know it'= s velocity as it approaches impact, it's easy enough to make sure that prov= ides precisely 6.78 joule of impact energy. If you can measure how much the glass is displaced by the impact, you get a= n extra bit of information about the strength of the surface you are testin= g. A bar-code etched into the side of the projectile and a pair of optical sen= sors looking at the bar code through a stationary grid pattern (one grid in= quadrature with the other) would do the job. The LED illuminating the bar = code would use up a bit of current, but it would only be active around impa= ct time. I'd go for a magnetic actuator, but for serious economy of power, use a spr= ing operated plunger, that the operator has to pull back against the spring= , and rely on the magnet only to adjust the impact energy during the period= after the catch has been released. Organising the electronics so that they= can come on and spring into full active life in the interval between the c= atch being released and the plunger hitting the glass might be challenging,= but it would maximise battery life. --=20 Bill Sloman, Sydney
On 27/06/2013 02:10, 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). > > Mark Harris >
A swinging weight on a pendulum - a Charpy Impact Tester - is repeatable and often used, but not small... http://en.wikipedia.org/wiki/Charpy_impact_test Or perhaps a pre-set calibrated automatic centre punch... http://en.wikipedia.org/wiki/Automatic_center_punch Cheers -- Syd
On Thursday, 27 June 2013 17:54:51 UTC+10, Syd Rumpo  wrote:
> On 27/06/2013 02:10, 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). > > > A swinging weight on a pendulum - a Charpy Impact Tester - is repeatable > and often used, but not small... > > http://en.wikipedia.org/wiki/Charpy_impact_test > > Or perhaps a pre-set calibrated automatic centre punch... > > http://en.wikipedia.org/wiki/Automatic_center_punch >
It turns out that my proposal is essentially an instrumented automatic centre punch ... -- Bill Sloman, Sydney
On Thu, 27 Jun 2013 01:52:34 -0700 (PDT), the renowned Bill Sloman
<bill.sloman@gmail.com> wrote:

>On Thursday, 27 June 2013 17:54:51 UTC+10, Syd Rumpo wrote: >> On 27/06/2013 02:10, 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). >> > >> A swinging weight on a pendulum - a Charpy Impact Tester - is repeatable >> and often used, but not small... >> >> http://en.wikipedia.org/wiki/Charpy_impact_test >> >> Or perhaps a pre-set calibrated automatic centre punch... >> >> http://en.wikipedia.org/wiki/Automatic_center_punch >> >It turns out that my proposal is essentially an instrumented automatic centre punch ...
The highly portable non-instrumented variety can be used to test the strength of the temperered glass used in car windows, as some who have parked their cars in the wrong place have discovered. 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 Wed, 26 Jun 2013 20:52:31 -0700, the renowned Jeff Liebermann
<jeffl@cruzio.com> wrote:

>On Thu, 27 Jun 2013 11:10:33 +1000, mharris@comprodex.com wrote: > >>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. > >Find a low friction ramp, and a method of supporting it perpendicular >to the panel. Roll a large steel bearing down the ramp. The energy >transferred will be controlled by the distance the ball is started up >the ramp, and the angle of the ramp. Some math will be required. This >is similar to the Charpy and Izod impact tests. No electronics >required.
Charpy/Izod tester was my first thought- it's complicated a bit by the variable panel orientation wrt gravity, and the usual machines are large. What about manually increasing compression on a spring (the pressure could be measured with an electronic gauge) to the desired value, then releasing the hammer mass with a manually operated pawl? If necessary you could correct for the force of gravity on the hammer mass with a tri-axis accelerometer, or manually with a table of settings for the approximate angle. 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 08:44:02 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

>On Wed, 26 Jun 2013 20:52:31 -0700, the renowned Jeff Liebermann ><jeffl@cruzio.com> wrote: >>Find a low friction ramp, and a method of supporting it perpendicular >>to the panel. Roll a large steel bearing down the ramp. The energy >>transferred will be controlled by the distance the ball is started up >>the ramp, and the angle of the ramp. Some math will be required. This >>is similar to the Charpy and Izod impact tests. No electronics >>required.
>Charpy/Izod tester was my first thought- it's complicated a bit by the >variable panel orientation wrt gravity, and the usual machines are >large. > >What about manually increasing compression on a spring (the pressure >could be measured with an electronic gauge) to the desired value, then >releasing the hammer mass with a manually operated pawl?
A can see a few problems with accuracy and calibration. I really don't know what degree of accuracy is required. The spring might vary a few percent with age, temperature, orientation, position of the moon, etc. The ramp is a little better, but changes in altitude (density of air) might have an effect if testing a solar panel on top of Mt Everest. Impact velocity could be easily measured with two photocells and a start/stop timer as the ball rolls down the ramp. Adjust the spring tension until the desired velocity is achieved. A bubble inclinometer should be sufficient for measuring tilt and adjusting the travel distance of the ball to compensate for the tilt. The specs should say something about the impactor contact area. Solar panel glass is tempered, which means that it's under tension on the surface. Break the tension with a sharp point, and the entire panel will shatter into tiny pieces of glass, even if the glass is glued to the solar cells. (I know because I've done it). I suspect the inclined ramp and ball idea may need to be modified into a pendulum or "rail car" style impactor to control the contact area.
>If necessary you could correct for the force of gravity on the hammer >mass with a tri-axis accelerometer, or manually with a table of >settings for the approximate angle.
Yep. Available off the shelf for the purpose: <http://www.ge-mcs.com/download/portable-and-diagnostic/286303.pdf> Just beat on the glass until it breaks. Then record the energy required. This could be fun. -- 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