July 11, 2002

 

Dear Dick:

 

I believe that we are going in the correct direction.  SLAC must be able

to analyze and predict the failure(s) before fixing the design.  All uncertainties in the analysis must be understood and accounted for, including flexure modeling, fastener fit-up, material property variability,

load uncertainty, etc. I would like a list generated of these uncertainties

and a mitigation strategy to address them.  In addition, I would like more assurance that the basic finite-element model is correct.  Previously, I requested model checks for 1-g loading (constraint forces total applied weight), free-free modes (rigid-body mode verification), and grounding.

 

Min Pham was asking about recovery of dynamic forces, applied vs. developed.

This should be included, too, in order to have confidence with the FEM.

 

I propose that SLAC puts together a chart addressing verification of the

FEM.  Previously, I asked for material properties of the carbon-carbon.  Theinformation provided is too sketchy for me to make a proper assessment.

Therefore, I am requesting the following carbon-carbon information:

 

      Manufacturer

      Fibers

      Fiber Architecture

      Densification Method

      % Theoretical Density

Purchasing Requirements (acceptance properties, workmanship requirements, inspection, certification testing, etc.)

      Design Allowables and Method of Determination

      Similar use of this material

 

      In addition, I am requesting the following information re the side panel composite:

 

      Prepreg manufacture

      Fiber

      Weave Description

      Resin

      Resin Content

      Purchasing Requirements

      Cure Process

      Fiber Volume

      Void Volume

      Laminate stacking sequence

      Inspection (NDE)

      Design Allowables

      Similar use of this material

 

      I am also concerned about the materials and processes used to produce the sidewall insert attachments.  For the aluminum insert, I want to know the following:

 

      Bond Preparation Data (Processes, Materials, Use of a Primer)

      Bonding Process (Fixturing, Bond line Control Method, Cure

Conditions)

 

Related to these, I want to know about the process used to make the holes in the carbon-carbon, hole inspection method and results, hole tolerance with the insert (relates to insert bond line).

      Lastly, I would appreciate more details on the inspection done on all the parts, composites, and subassemblies.

 

Regards,

 

Ben Rodini