Home NRC Library Document Collections Events, Reports Associated with Part 21 Reports 1998

Part 21 Report - 1998-138

ACCESSION #: 9808030039

Shared Services Group
P.O. Box 3707
Seattle, WA 98124-2207

BOEING

July 24, 1998
G-1151-SJA-98-372

Document Control Desk
United States Nuclear Regulatory Commission
Washington, D.C. 20555

Reference:	a)	Boeing Letter G-1151-RSO-92-365 dated August 31, 1992; R.S. Orr to the NRC Operations Center
	b)	NRC Letter Docket No. 99901227 dated August 12, 1992; L. J. Norrholm to R. S. Orr; Subject: Response to 10 CFR 21 Inquiry

Dear Sir or Madam:

In accordance with the reference correspondence and 10 CFR 21, Boeing is sending the NRC the attached error notice(s) received from our former software suppliers. Because of unknown current addresses, the following former customers were not notified:

Reactor Controls, Inc.
Echo Energy Consultants, Inc.
Nuclear Applications and Systems Analysis Company (Japan)
Nuclear Power Services

Error notices have been sent to our other former customers.

Very truly yours,

Sandra J. Andrews
Nuclear Administrator
Phone: (425) 865-6248
FAX: (425) 865-4851
Mail Stop: 7A-33, or
e-mail: Sandra.J.Andrews@Boeing.com

Enclosure(s): ANSYS Class 3 Error Report

ANSYS**[Registered trademark]

ANSYS, Inc.
Southpointe
275 Technology Drive
Canonsburg, PA 15317

July 8, 1998

Dear Class3 Error Recipient:

Enclosed you will find ANSYS Class3 Error Reports 98-13 through 98-17, Class3 Error Report 98-08 R1, ANSYS QA Notice QA98-07 and Support Coordinator Bulletins SCB98-02 R1, SCB98-03 and SCB98-04 R1. These reports were issued in the second quarter of 1998.

Also included with this Class3 Error mailing is a memo which details the hardware and platform support for ANSYS Release 5.5.

Revised Class3 Error Report

Class 3 Error Report 98-08 R1 has been issued to clarify some wording in the description of the error.

QA Notice

QA Notice QA98-07 was issued for Release 5.4 because the program behavior could lead a user to expect element shape retesting in all cases, even through it is not stated in the documentation.

Support Coordinator Bulletins

ANSYS Support Coordinator Bulletin SCB98-02 R1 has been issued to give users further details about an occasional and apparently random error occurring on the Sun version of ANSYS Release 5.4 which causes ANSYS to run indefinitely.
ANSYS Support Coordinator Bulletin SCB98-03 his been issued to inform users of the improvements that have been made to the method used for convergence checking in the Preconditioned Conjugate Gradient (PCG) Solver for the case of linear static analysis with H-elements and the affect on solution convergence printout.
ANSYS Support Coordinator Bulletin SCB98-04 R1 has been issued to quantify for users the documented stress inaccuracy which may be introduced for warped shell elements with thermal loads. Note that the original Support Coordinator Bulletin SCB98-04 was only issued electronically and was never issued in hardcopy form. The modification made in the re-issue of SCB98-04 is the addition of a statement that SHELL63 should not be used as a workaround for nonlinear analysis.

I would like to remind you of the various ways that you can receive Class3 error information. Quarterly, Class3 errors will be delivered by mail to the ANSYS Support Coordinator listed on your ANSYS license agreement. Please notify your ASD of any personal or address changes that should be incorporated into our record for your ANSYS agreement in order to avoid any interruptions in receiving your Class3 Error Report mailings.

Class3 Errors and QA Notices are posted on ANSYS's Internet HomePage. The address is http://www.ansys.com. They are located in the ANSYS Zone section of the HomePage under Customer. The username to enter this area is "customer" and the password is "ain1fm" (ANSYS is number 1 for me).

Finally, users desiring access to Class3 errors on a more timely basis you can be added to our email distribution list. To register for email notification of reports, simply send an email request including your email address, company name/address and ANSYS agreement number to bonny.podolek@ansys.com. If you are a current subscriber to email distribution, please keep us informed of any changes in your email address by emailing bonny.podolek@ansys.com. After two failed transmissions, your name will be removed from the distribution list.

For your convenience, also enclosed with this mailing you will find ANSYS Class3 Error Summary Reports sorted both by error number and keyword for Release 5.3 and Release 5 4.

Sincerely,

William J. Bryan
Quality Assurance Manager

ANSYS [Registered trademark] CLASS3 ERROR REPORT

ERROR NO: 98-13

KEYWORDS;

ELEM20
PIPE20
THERMAL LOADING
NEWTON-RAPHSON

DESCRIPTION OF ERROR:

All results are incorrect if PIPE20, the plastic straight pipe element is used with nonzero thermal strains and the Newton-Raphson option is used. The magnitude of the error is in proportion to the magnitude of the thermal strains from the previous substep. The normal nonlinear usage of the element uses the Newton-Raphson option.

TYPICAL GUI PATH(S):

Preprocessor>Create>Elements>Elem Attributes

FIRST INCORRECT VERSION(S):*_/ CORRECTED IN:*_/

Revision 5.0		Release 5.5
SUGGESTED USER ACTION FOR RUNNING ON UNCORRECTED VERSION:
COMMENTS:
AUTHOR/CORRECTOR:			DATE: May 20, 1998
	Peter Kohnke
REVIEWED BY QA:			DATE: May 20, 1998
	William J. Bryan
APPROVAL:			DATE: May 20, 1998
	David L. Conover

-------------

Unless noted otherwise, this error report also applies to all releases after the first incorrect one and prior to the corrected release. All releases after "corrected In" are corrected. Manual corrections are included in on-line documentation as appropriate. Please see the reverse side of this sheet for additional information on ANSYS release identifiers.

ANSYS Release Identifier Description

ANSYS release identifiers consist of a major release level, a minor release level, a correction and a build date. An example of how this is constructed is shown below:

	5.3 UP030797	<--- build date (form = Upmmddyy)
	^ ^ \| \| \| \|
	major release level	-- -- minor release level

Major release level changes indicate that new features have been added to the program and that some level of program architecture change and/or file structure may have occurred. Minor release level changes also indicate that new features have been added to the program, but files are upwardly compatible. All known error fixes are included in both minor and major releases. The build date corresponds to the date the program was created. Special versions may be provided to circumvent and error and are identified by build date. Special versions are not general releases to all ANSYS licensees, since they typically represent error corrections occurring only on one system, a subset of our customers who have specific graphics devices, etc.

When a release identifier on a Class3 Error Report does not include a build date, all build dates for the indicated release level are included. When a release identifier for FIRST INCORRECT VERSION explicitly includes a build date, the release level with the indicated build date as well as all earlier build dates for that release level are affected. When a release identifier for CORRECTED IN explicitly includes a build date, the release level with the indicated build date as well as all subsequent build dates contain the correction.

For example, a Class3 Error report with "5.3 UP100396" for FIRST INCORRECT VERSION and "5.5 UP063098" for CORRECTED IN" would apply to all 5.3 releases with a build date UP100396 or later, all 5.4 releases (regardless of build date) and all 5.5 releases with a build date earlier than UP063098.

The ANSYS release identifier(s) shown under "corrected in" on the front side of Class3 Error reports indicates the first possible release that contains the correction.

An identifier indicated under "corrected in" does not guarantee that a general distribution of that release of ANSYS will occur. It does indicate that the correction is known and implemented in that or any subsequent release.

Product Applicability

The ANSYS family of component products occasionally undergoes name changes between releases and/or changes in the functionality of derived products (such as ANSYS-PC/LINEAR). To minimize the potential for confusion in these areas, unless otherwise noted on the front side of the Class3 Error Report, the error report applies to all ANSYS family products (including standalone component products) that contain the described features(s) in the designated release(s).

ANSYS [Registered trademark] CLASS3 ERROR REPORT

ERROR NO: 98-14

KEYWORDS: THERMAL LOAD NEWTON RAPHSON REFERENCE TEMPERATURE

DESCRIPTION OF ERROR:

The z-strain (EPELZ) will be incorrect if a SHELL43, SHELL93, or SHELL143 is used, or if a plane stress option of PLANE2, PLANE13, PLANE42, or PLANE82 is used and Newton-Raphson is used (e.g. NLGEOM.ON or plasticity is being used, or a contact element type is present): and a load step has all of the temperatures of an element equal to the reference temperature: and the previous load step has at least one temperature of an element not equal to the reference temperature.

This error has also been seen to change the number of iterations needed for convergence as well as to rarely have a significant effect on nonlinear problems. The magnitude of the error is proportional to the thermal strains in the previous load step.

TYPICAL GUI PATH(S):

FIRST INCORRECT VERSION(S):*_/ CORRECTED IN:*_/

Revision 5.0		Release 5.5
SUGGESTED USER ACTION FOR RUNNING ON UNCORRECTED VERSION:
	Rerun and change the temperature of the suspect load step from TREF to TREF + 1.0e-8.
COMMENTS:
AUTHOR/CORRECTOR:		DATE: May 20, 1998
	Peter Kohnke
REVIEWED BY QA:		DATE: May 20, 1998
	William J. Bryan
APPROVAL:		DATE: May 20, 1998
	David L. Conover

-----------

*_/Unless noted otherwise, this report applies to all ANSYS family products which contain the described feature in the indicated Release(s). See the reverse side for details regarding product applicability). Unless noted otherwise, this error report also applies to all releases after the first incorrect one and prior to the corrected release. All releases after "corrected in" are corrected. Manual corrections are included in on-line documentation as appropriate. Please see the reverse side of this sheet for additional information on ANSYS release identifiers.

ANSYS Release Identifier Description

ANSYS release identifiers consist of a major release level, a minor release level, a correction and a build date. An example of how this is constructed is shown below:

	5.3 UP030797	<--- build date (form = Upmmddyy)
	^ ^ \| \| \| \|
	major release level	-- -- minor release level

Major release level changes indicate that new features have been added to the program and that some level of program architecture change and/or file structure may have occurred. Minor release level changes also indicate that new features have been added to the program, but files are upwardly compatible. All known error fixes are included in both minor and major releases. The build date corresponds to the date the program was created. Special versions may be provided to circumvent an error and are identified by build date. Special versions are not general releases to all ANSYS licensees, since they typically represent error corrections occurring only on one system, a subset of our customers who have specific graphics devices, etc.

When a release identifier on a Class3 Error Report does not include a build date, all build dates for the indicated release level are included. When a release identifier for FIRST INCORRECT VERSION explicitly includes a build date, the release level with the indicated build date as well as all earlier build dates for that release level are affected. When a release identifier for CORRECTED IN explicitly includes a build date, the release level with the indicated build date, as well as all subsequent build dates contain the correction.

For example, a Class3 Error Report with "5.3 UP100396" for FIRST INCORRECT VERSION and "5.5 UP063098" for "CORRECTED IN" would apply to all 5.3 releases with a build date UP100396 or later, all 5.4 releases (regardless of build date) and all 5.5 releases with a build date earlier than UP063098.

The ANSYS release identifier(s) shown under "corrected in" on the front side of Class3 Error reports indicates the first possible release that contains the correction.

Product Applicability

Report, the error report applies to all ANSYS family products (including standalone component products) that contain the described features(s) in the designated release(s).

ANSYS [Registered trademark] CLASS3 ERROR REPORT

ERROR NO: 98-15

KEYWORDS:

LS-DYNA
PRNSOL
EPTO
PRIN

DESCRIPTION OF ERROR:

Strains from LS-DYNA are tensorial values rather than engineering values. In computing equivalent strains ANSYS assumes that the strains are engineering strains (i.e. shear strains are multiplied by a factor of 2). As a consequence, the value of the equivalent strains EQV and shear strains are incorrect.

TYPICAL GUI PATH(S):

Post-Processor>Plot Results

FIRST INCORRECT VERSION(S):*_/ CORRECTED IN:*_/

Revision 5.3		Release 5.5
SUGGESTED USER ACTION FOR RUNNING ON UNCORRECTED VERSION:
	None
COMMENTS:
AUTHOR/CORRECTOR:		DATE: June 10, 1998
	Makarand Kulkarni
REVIEWED BY QA:		DATE: June 10, 1998
	William J. Bryan
APPROVAL:		DATE: June 10, 1998
	David L. Conover

-----------

Unless noted otherwise, this error report also applies to all releases after the first incorrect one and prior to the corrected release. All releases after "corrected in" are corrected. Manual corrections are included in on-line documentation as appropriate. Please see the reverse side of this sheet for additional information on ANSYS release identifiers.

ANSYS Release Identifier Description

ANSYS release identifiers consist of a major release level, a minor release level, a correction and a build date. An example of how this is constructed is shown below:

	5.3 UP030797	<--- build date (form = Upmmddyy)
	^ ^ \| \| \| \|
	major release level	-- -- minor release level

Major release level changes indicate that new features have been added to the program and that some level of program architecture change and/or file structure may have occurred. Minor release level changes also indicate that new features have been added to the program, but files are upwardly compatible. All known error fixes are included in both minor and major releases. The build date corresponds to the date the program was created. Special versions may be provided to circumvent an error and are identified by build date. Special versions are not general releases to all ANSYS licensees, since they typically represent error corrections occurring only on one system, a subset of our customers who have specific graphics devices, etc.

The ANSYS release identifier(s) shown under "corrected in" on the front side of Class3 Error reports indicates the first possible release that contains the correction.

Product Applicability

ANSYS [Registered trademark] CLASS3 ERROR REPORT

ERROR NO: 98-16

KEYWORDS:

LS-DYNA
SHELL163

DESCRIPTION OF ERROR:

For SHELL163, stresses are incorrect if the number of integration points through the thickness is a multiple of 11.

TYPICAL GUI PATHS:

Main Menu>General Postproc>List Results>Nodal Solution

Utility Menu>List>Results>Nodal Solution

FIRST INCORRECT VERSION(S):*_/ CORRECTED IN:*_/

Revision 5.4		Release 5.6
SUGGESTED USER ACTION FOR RUNNING ON UNCORRECTED VERSION:
	Use a number of integration points (through the thickness) that is not a multiple of 11.
COMMENTS:	None
AUTHOR/CORRECTOR:		DATE: June 10, 1998
	Makarand Kulkarni
REVIEWED BY QA:		DATE: June 10, 1998
	William J. Bryan
APPROVAL:		DATE: June 10, 1998
	David L. Conover

-----------

*_/Unless noted otherwise, this report applies to all ANSYS family products which contain the described feature in the indicated Release(s) See the reverse side for details regarding product applicability).

ANSYS Release Identifier Description

ANSYS release identifiers consist of a major release level, a minor release level, a correction and a build date. An example of how this is constructed is shown below:

	5.3 UP030797	<--- build date (form = Upmmddyy)
	^ ^ \| \| \| \|
	major release level	-- -- minor release level

Major release level changes indicate that new features have been added to the program and that some level of program architecture change and/or file structure may have occurred. Minor release level changes also indicate that new features have been added to the program, but files are upwardly compatible. All known error fixes are included in both minor and major releases. The build date corresponds to the date the program was created. Special versions may be provided to circumvent an error and are identified by build date. Special versions are not general releases to all ANSYS licensees, since they typically represent error corrections occurring only on one system, a subset of our customers who have specific graphics devices, etc.

The ANSYS release identifier(s) shown under "corrected in" on the front side of Class3 Error reports indicates the first possible release that contains the correction.

Product Applicability

ANSYS [Registered trademark] CLASS3 ERROR REPORT

ERROR NO: 98-17

KEYWORDS:

WINDOWS
GUI
CUT
PASTE
SYSTEM

DESCRIPTION OF ERROR:

On Windows systems, if more than one ANSYS input line is cut or copied (cntrl-x or cntrl-c) and then pasted (cntrl-v) into the input window of the GUI, then the last line may have extra characters added. While most of the time it is obvious, this can produce unexpected results.

TYPICAL GUI PATH(S):

Many

FIRST INCORRECT VERSION(S):*_/ CORRECTED IN:*_/

Rev. 5.1		Release 5.5
SUGGESTED USER ACTION FOR RUNNING ON UNCORRECTED VERSION:
	If text is cut or copied (cntrl-x or cntrl-c) from a file and pasted (cntrl-v) into the ANSYS Input Window, the carriage return and line feed at the end of the last line must be included. To ensure this, highlight past the end of the last line.
COMMENTS:
AUTHOR/CORRECTOR:		DATE: July 2, 1998
	Cindy Podlaszewski
REVIEWED BY QA:		DATE: July 2, 1998
	William J. Bryan
APPROVAL:		DATE: July 2, 1998
	David L. Conover

-----------

ANSYS Release Identifier Description

ANSYS release identifiers consist of a major release level, a minor release level, a correction and a build date. An example of how this constructed is shown below:

	5.3 UP030797	<--- build date (form = Upmmddyy)
	^ ^ \| \| \| \|
	major release level	-- -- minor release level

Major release level changes indicate that new features have been added to the program and that some level of program architecture change and/or file structure may have occurred. Minor release level changes also indicate that new features have been added to the program, but files are upwardly compatible. All known error fixes are included in both minor and major releases. The build date corresponds to the date the program was created. Special versions may be provided to circumvent an error and are identified by build date. Special versions are not general releases to all ANSYS licensees, since they typically represent error corrections occurring only on one system, a subset of our customers who have specific graphics devices, etc.

The ANSYS release identifier(s) shown under "corrected in" on the front side of Class3 Error reports indicates the first possible release that contains the correction.

Product Applicability

ANSYS [Registered trademark] CLASS3 ERROR REPORT

ERROR NO: 98-08 R1

KEYWORDS:

PLANE 25
NEWTON-RAPHSON

DESCRIPTION OF ERROR:

All results are incorrect for PLANE25, the 4-node axisymmetric-harmonic structural solid element, if:

1. the previous load step had a different value of MODE or ISYM (MODE command) than the present load step: and

2. the Newton-Raphson option is active ([Redline: needed for nonlinear analysis).]

[Strikeout: Examples of when] The Newton-Raphson option is active when [strikeout: stress stiffening or] element birth and death is present or when a gap element type has been included.

TYPICAL GUI PATH(S):

Main Menu>Solution>Other>ForHarmonicEle

FIRST INCORRECT VERSION(S):*_/ CORRECTED IN:*_/

Revision 5.4		Release 5.5
SUGGESTED USER ACTION FOR RUNNING ON UNCORRECTED VERSION:
	Consider using PLANE83, the 8-node axisymmetric structural solid element.
COMMENTS:	An error message will appear at Release 5.5 for this condition.
	The use of axisymmetric-harmonic elements for nonlinear problems is very limited, as these elements presume that the entire model is linear.
AUTHOR/CORRECTOR:		DATE: June 11, 1998
	Peter Kohnke
REVIEWED BY QA:		DATE: June 11, 1998
	William J. Bryan
APPROVAL:		DATE: June 11, 1998
	David L. Conover

-----------

ANSYS Release Identifier Description

ANSYS release identifiers consist of a major release level, a minor release level, a correction and a build date. An example of how this is constructed is shown below:

	5.3 UP030797	<--- build date (form = Upmmddyy)
	^ ^ \| \| \| \|
	major release level	-- -- minor release level

Major release level changes indicate that new features have been added to the program and that some level of program architecture change and/or file structure may have occurred. Minor release level changes also indicate that new features have been added to the program, but files are upwardly compatible. All known error fixes are included in both minor and major releases. The build date corresponds to the date the program was created. Special versions may be provided to circumvent an error and are identified by build date. Special versions are not general release to all ANSYS licensees, since they typically represent error corrections occurring only on one system, a subset of our customers who have specific graphics devices, etc.

The ANSYS release identifier(s) shown under "corrected in" on the front side of Class3 Error reports indicates the first possible release that contains the correction.

Product Applicability

ANSYS QA NOTICE

NOTICE NO: QA98-07

SUBJECT:

ET
ETCHG
KEYOPT
SHAPE TESTING

DESCRIPTION:

Element shape testing may not trap poorly shaped elements if the user changes the element type specification after elements of the given type have already been created. This notice is being issued for Release 5.4 because the program behavior could lead a user to expect retesting, even though it is not promised by the documentation.

More specifically, if elements of a given element type (ITYPE on the ET command) exist when their corresponding element name or number (Ename on the ET command) is redefined to be a new number, or when an element option is changed (KOP1 etc. on the ET command or VALUE on the KEYOPT command), then the existing elements are not retested against the shape limits for the new element type or options.

There are four commands that can change the Ename or options of existing elements. The EMODIF command works correctly, and is discussed below. The other three commands fail to correctly retest existing elements:

1. The ETCHG command initiates no retesting.

2. The KEYOPT command initiates no retesting.

3. The ET command uses the shape criteria for the old element name or number and options for retesting, rather than the criteria for the new element name or number and options

Typical GUI Path(s):

Preprocessor>Element Type>Add/Edit/Delete>Options
Preprocessor>Element Type>Switch Elem Type

AFFECTED VERSIONS: Release 5.4 - Release 5.5

SUGGESTED USER ACTION:

1. Define a new element type with the desired Ename and options, then use the EMODIF command to change, the ITYPE of the existing elements, which will be properly retested:

2 After changing the Ename or options of existing elements, issue the following commands to force the retesting of all elements.

SHPP.OBJECT.OFF
CHECK.......ESHAPE

COMMENTS:

1.	A given element shape may be perfectly valid for one element type but excessively distorted for another. For example, SHELL63 elements having corner angles of 45 degrees are not a problem (assuming nothing else is wrong with the element shape), but if those elements were switched to SHELL28s, the corner angle deviation from 90 degrees would be well beyond the error limit. As a result of this error, element shape warnings or errors may not be issued for elements shapes that need it.
2.	Element shape testing was improved extensively at ANSYS Release 5.4. In prior releases, some shape tests were always performed at solution, but no systematic retesting was done under any of the conditions listed above.

Author:		Date May 14, 1998
	F.S. Kelley
Reviewed by QA:		Date May 14, 1998
	William J. Bryan
Approval:		Date May 14, 1998
	David L. Conover

ANSYS SUPPORT COORDINATOR BULLETIN

SCB 98-02 R1

KEYWORDS:

MULTI-PROCESSING
SUN SYSTEM
SOLUTION

When executing in multi-processor mode [number of processors> 1], occasionally and apparently randomly, the Sun version of ANSYS 5.4 runs indefinitely, (i.e. never completes) during ANSYS solution. If this occurs, we recommend that you run the solution again in single-processor mode [number of processors=1]. The number of processors can be specified via /CONFIG,NPROC or by NUM_PROC keyword in the start.ans file.

We have worked extensively with Sun's technical staff to understand and resolve this issue. It appears to have been corrected with Solaris 2.6. For many sites, this operating system upgrade has eliminated these random occurrences. Sun Microsystems and ANSYS, Inc. recommend that the Sun operating system be upgraded to Solaris 2.6.

Author:		Date: July 8, 1998
	Sam Murgie
Reviewed by QA:		Date: July 8, 1998
	William J. Bryan
Approval:		Date: July 8, 1998
	David L. Conover

ANSYS SUPPORT COORDINATOR BULLETIN

NOTICE NO: SCB98-03

SUBJECT:

PCG SOLVER
CONVERGENCE TOLERANCE
LINEAR STATIC

DESCRIPTION:

In the 5.4 Release of ANSYS, improvements have been made to the method used for convergence checking in the Preconditioned Conjugate Gradient (PCG) Solver for the case of linear static analysis with H-elements. These improvements result in faster convergence for a given solution accuracy for this class of analyses. The PCG solver convergence is now based on a comparison of multiple convergence norms to internally calculated convergence tolerances that are based on the user supplied convergence tolerance value (TOLER on the EQSLV command). The solution is found to be converged when two of the convergence criteria are met (one of which may be based on the convergence criteria that was used in previous releases of ANSYS).

It should be noted that the CALCULATED NORM and TARGET NORM output items are from the same convergence criteria (the one that was used in previous releases) in all cases whether or not it is the actual criteria that indicated convergence. Thus, these output items (on the output file and the convergence status bar in the GUI) may appear to indicate improper convergence in some cases. Beginning with the 5.5 release of ANSYS, rather than outputting the norms for this same convergence criteria in all cases, the smallest of the norms from the criteria that indicated convergence will be output.

Because all of the internally calculated convergence tolerances are based on the user specified solution tolerance, any change to the user supplied tolerance will change the internal tolerances by a proportional amount.

AUTHOR:		DATE: June 10, 1998
	Ken Podlaszewski
REVIEWED BY QA:		DATE: June 10, 1998
	William J. Bryan
APPROVAL:		DATE: June 10, 1998
	David L. Conover

Page 1 of 3

ANSYS SUPPORT COORDINATOR BULLETIN

NOTICE NO: SCB98-04 R1

SUBJECT:

SHELL43
SHELL91
SHELL93
SHELL99
SHELL 143
CURVED SHELLS
THERMAL LOADING

If a curved or warped shell structure is subjected to thermal loads

and:

1. the shell is relatively thick, and 2. the shell is modeled with one of the following shell elements:

          - SHELL43 (the Plastic Large Strain Shell),
          - SHELL91 (the 16-Layer Structural Shell),
          - SHELL93 (the 8-Node Structural Shell),
          - SHELL99 (the 100-Layer Structural Shell),
          - SHELL143 (the Plastic Shell),

then the stress error introduced by the thick-shell effects may be significant. Note that this restriction in these elements' formulation is documented in the ANSYS Elements Manual under the "Assumptions and Restrictions" section. Although this is a known restriction, it is not obvious hence the reason for this Support Coordinator Bulletin. This restriction will be removed at Release 6.5 for SHELL43 and 93.

The attached figure provides information on the magnitude of the stress error introduced. The figure plots the maximum stress error in the equivalent stress SEQV versus the radius-to-thickness ratio R/t. The stress error has been normalized to the pure thermal stress, E*alpha*deltaT, where E is Young's Modulus [EX on the MP command], alpha is the

coefficient of thermal expansion (MP,ALPX] and deltaT is the temperature differential T - Tref. T is the applied temperature and Tref is the reference temperature [TREF command or MP,REFT]. These figures are obtained by solving cylindrical and spherical shells subjected to uniform thermal expansion and obtaining the maximum SEQV value in the model for various mesh discretizations (the error is essentially independent of the mesh size).

For thin shells (large R/t ratios), the error is small. Likewise, for small thermal strains (alpha*deltaT), the error is also small. It is only for relatively thick shells subjected to large thermal strains where the error becomes significant.

Page 2 of 3

SCB98-04 R1

AFFECTED RELEASES: Revision 4.0 through Release 5.4

SUGGESTED USER ACTION:

Run the model with free thermal expansion and observe the maximum stress (which should be zero). If the stress is too large, switch the shell element types to SHELL63 or SHELL181. [Redline: Note that SHELL63 with thermal loads should not be used for nonlinear analysis; see Class3 Error reports 96-14 and 98-03 for details].

OTHER COMMENTS:

Thermal loads are introduced when any specified temperature is not equal to Tref [TREF command or MP,REFT] and when any coefficient of thermal expansion is greater than zero [e.g. MP,ALPX].

SHELL43 and SHELL143 do not exhibit this limitation if all four nodes lies in a plane (the element is not warped), such as when modeling a cylindrical shell where the element edges align with constant cylindrical theta coordinates and constant Z coordinates. Note that in a large deflection analysis (NLGEOM,ON), initially flat elements may end up warped.

AUTHOR:		DATE: June 12, 1998
	David L. Conover
REVIEWED BY QA:		DATE: June 12, 1998
	William J. Bryan
APPROVAL:		DATE: June 12, 1998
	Mark C. Imgrund

Figure "Stress Error vs. R/t"

July 2, 1998

Dear Valued Customer:

This letter contains corrections and clarifications regarding Hardware and System Support for ANSYS 5.5 (see attached table). It is an update to the 20 March 1998 letter sent to you. Several important changes have occurred. The operating system levels for the IBM RS/6000 and Digital Alpha UNIX have been corrected to AIX 4.3.1 and Digital UNIX 4.0B, respectively. The Cray operating system level has been revised to UNICOS 10.0. Also, the Sun platforms have been revised to a newer operating system level. Solaris 2.6, and we have added support for the newly released PC operating system, Windows98. The Sun operating system change has been necessitated by a sporadic 'sleep state' problem that several users were experiencing. Please refer to Support Coordinator Bulletin SCB 9842 R1 for details.

ANSYS 5.5 is currently in beta release, and is scheduled for Q3 1998 commercial availability.

Sincerely,

Frank J. Marx, PE
Manager, ANSYS Products
Hardware and System Support for ANSYS 5.5

The table below lists the hardware and the appropriate operating system level for the ANSYS 5.5 Family of Products. ANSYS/LS-DYNA runs on a limited set of these platforms as indicated in the table. The operating system levels that are new or different from ANSYS 5.4 are preceded by an asterisk (*).

Where: Large memory, large file support indicates RAM addressing up to 8 GB and file sizes up to the operating system's limit.

Platforms NOT supported at 5.5 are:

CRAY J90
CRAY YMP
Digital Alpha Windows NT 3.51
HP/Convex Exemplar
Intel PC Windows NT 3.51

All platforms (except the Cray C90 and T90) are expected to be released in Q3, 1998.

Please Note: The license server(s) must be one of the supported 5.5 systems.

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