[Solid_ec] module stress calculation (rod+sheet design)

[Xiaochao Zheng]

Dear Cunfeng:

Thanks. You are right about (1). I will change the calculation accordingly.

For 2), it's just a design idea at the moment. The ANL engineer suggested it at the first place. We can certainly keep the small hole design for both endplates if the compression is a concern.

3) Using nuts is just an alternative option. It's not preferred, but can be used just in case.

For 4), the spring reed is a good suggestion. OUr modules are all the same length so the side sheets can be the same as well. We should use six sheets/module for sure, since our design has a hexagon shape. 

For 5), we can only suspend all modules from the back.  There had been calculation to show that if we have another support sheet in between preshower and shower, it has to be 2cm thick (for aluminum) at the least and will affect the PID performance. Anything thinner will not hold the weight of the module. The rod is necessary for fixing the modules to the back support plate, otherwise I do not know how to fix them. ALICE also used the back support only and their modules are placed in a solenoid field. However, so far I do not know how ALICE support their modules (I emailed the LBNL engineer but have not heard any reply).  If you can think of other methods to support/fix the module from the back, I will certainly consider them and compare them with the rod-support design.

Thanks!

Xiaochao

----- Original Message -----
From: "Cunfeng Feng" <cfeng at cern.ch>
To: "solid ec" <solid_ec at jlab.org>
Sent: Thursday, November 26, 2015 9:34:43 PM
Subject: Re: [Solid_ec] module stress calculation (rod+sheet design)

Dear Xiaochao, 

Thanks for your detail calculation. Even I don't understand all the terms fully, I have comment on your results as follows: 
1) The ideal length is 194*(1.5+0.5+2*0.12)=434.56mm, plus both 6mm endplates, the total length is 447mm. I don't understand how you get 481mm. 

2) I don't agree on the big hole on the bottom endplate. The pressure is put on the module through this endplate, the big hole will lead the force nonuniform on the scintillor , and will break the scitilltors. In fact, the fiber can be insert into the module through the small holes as your original draft, not the big hole. 

3) We will use the assemble tool to provide the 500kg/1000kg compression as Alice did, instead of the 2.5mm nuts. 

4) Alice EMCal only use 4 side sheets for each module, no bar inside. If we plan to use side sheets also, do we still need the 2.5mm bar? As I know from Alice also, they use the same length side sheets for all the modules. If the module is shorter than the sheet, they will add some meterial(forget what's it). They also put few spring reed(蝶形簧片) between the endplates inside the module to keep tension of the sheets. 

5) As your plot show us, many shashlyk modules will be mounted on one big support plate from the top endplate. I don't know how importan for the experiment to use this one side support scheme. I think it will be ease for us to design the module with two end support scheme. In order to reach enough support strength, I believe two end support need less material than one end support. 


Cheers, 
Cunfeng 

在 2015/11/25 6:04, Xiaochao Zheng 写道: 



Dear All:

I thought about the module assembling process and various requirements on the compression, load, supporting, etc.  I have attached some calculation and preliminary assembling process design. The module structure is attached in a separate PDF file. (For some reason I could not import the image into WORD without distorting it.)

Please send me comments.

Thanks,

Xiaochao

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