SoHaR RAMS team performs
reliability prediction for
electronic and non-electronic parts according
to any of the existing
reliability standards and manufacturer
in-house data. Reliability calculations are
based on the electrical/thermal stress
analysis. The output is a report with a
breakdown of MTBF (Mean Time Between Failures)
and MTBCF (Mean Time Between Critical
Failures) figures per system, unit, board and
component levels. The reliability figures of
"Buy" items are incorporated into prediction
after adjustment to a particular environment
and temperature condition.
Reliability Prediction Methods and
Models
Our reliability team is proficient in
reliability prediction methods listed below.
These methods are also supported by our
reliability prediction software - RAM
Commander.
MIL-HDBK-217 Part Stress & Part Count
MIL-HDBK-217 Module for Parts Stress
reliability prediction of electronic equipment
based on MIL-HDBK-217 E, F, F Notice 1, F
Notice 2, published by Department of Defence,
USA.
MIL-HDBK-217 Parts Count reliability
prediction Module based on MIL-HDBK-217 E, F
Notice 1, F Notice 2 methods for Parts Count.
217Plus - Based on Handbook of 217PlusTM
Reliability Prediction Models, 26 May 2006
by Reliability Information Analysis Centre (RIAC).
BEL - BellCore - Module for reliability
prediction based on Bellcore document
TR-NWT-000332, (Issue 4, Issue 5, Issue 6).
Telcordia - Telcordia SR332, Issue 1,
May 2001
Telcordia Issue 2 - Reliability
Prediction Procedure for Electronic Equipment,
SR-332, Issue 2, September 2006
CNET RDF 93 Revision 2/95
Module for reliability prediction based on
CNET, French reliability prediction method for
commercial applications.
UTE C 80810, RDF 2000, IEC 62380
RDF 2000 (UTEC 80810) is the new version
of the French reliability prediction standard
that covers most of the same components as
MIL-HDBK-217. In RDF 2000 the difficult to
evaluate environment factor is replaced by
equipment mission profiles and thermal
cycling. RDF2000 provides complex models that
can handle permanent working, on/off cycling
and dormant applications. As this standard
becomes more widely used it could become the
international successor to the US
MIL-HDBK-217.
IEC 62380 (RDF 2003)
Updated version of RDF 2000 UTEC 80810
method – French Telecom reliability prediction
Standard. It includes most of the same
components as MIL-HDBK-217. Since it is
difficult to evaluate the environmental
factor, RDF 2000/2003 uses equipment mission
profiles and thermal cycling for evaluation.
RDF2000/2003 provides complex models that can
handle permanent working, on/off cycling and
dormant applications. As this standard becomes
more widely used, it could become the
international successor to the US
MIL-HDBK-217.
FIDES Guide 2009
This method replaces the FIDES Guide
2004 issue A (also published by the UTE under
reference UTE-C 80811). The FIDES methodology
is applicable to all domains using
electronics: aeronautical, naval, military,
production and distribution of electricity,
automobile, railway, space, industry,
telecommunications, data processing, home
automation, household appliances Etc.
The FIDES methodology covers items varying
from an elementary electronic component to a
module or electronic subassembly with a
well-defined function. Coverage of item
families by FIDES is not absolutely
exhaustive. However, the coverage is broadly
sufficient to make a representative evaluation
of reliability in most cases.
The methodology is applicable to COTS items
(for which it was initially developed), but
also to special items provided that their
technical characteristics comply with the
technical characteristics.
The FIDES methodology models failures with
origins intrinsic to the studied items and
extrinsic specification and design of the
equipment, selection of the equipment
procurement, production and integration
system).
The methodology takes account of:
The FIDES methodology deals with
non-functioning phases, either during dormant
periods between use, or genuine storage.
BRT - British Telecom - British Telecom
Module for reliability prediction based on
British Telecom document HRD-4 or HRD-5.
GJB299 - Chinese reliability standard
both Part Stress and Part Count.
Siemens SN29500.1 - Siemens reliability
standard
Siemens SN 29500-2005-1 -
Siemens reliability standard updated version
RADC-TR-85-91 Non-operating Reliability
Prediction
Module for calculating non-operating
failure rates based on RADC TR-85-91. The data
necessary for this calculation is actually a
subset of the data for calculation of
operating failure rates. Thus, no additional
data entry is required to run RADC-TR-85-91.
This module also allows for non-operating
mission phases, thus providing Mission Profile
Analysis with Non-operating Prediction.
NPRD-95 Non-electronic Parts Reliability
Data
NPRD-95 module contains a library of
failure rates for a large number of
non-electronic components under various
environments. The source of this data is the
document NPRD-95, "Non-electronic Parts
Reliability Data", released by RAC.
Part category which provides a rough
classification of parts (e.g., actuators,
batteries, pumps, etc.) should be selected for
each device. Next, the user selects a certain
subtype (e.g., for batteries - Carbon Zinc,
Lithium, etc.).
If the failure rate for required environment
does not appear on the list, the failure rate
for some other environment can be used. When
the item type is defined, it is possible to
view a list of component failure rates for
different environments and Quality levels, if
corresponding data exist in NPRD-95.
NSWC-98 Handbook of Reliability Prediction
Procedures for Mechanical Equipment
This handbook by the US NAVY presents an
approach for determining the reliability
characteristics of mechanical equipment. The
design evaluation techniques program initiated
by the Carderock Division of the Naval Surface
Warfare Centre includes a methodology for
evaluating a design for R&M that considers the
material properties, operating environment and
critical failure modes at the component level.
Nineteen basic mechanical components have been
identified for which reliability prediction
equations have been developed. All mechanical
equipment is composed of some combination of
these nineteen components. A designer can
utilize the equations to determine individual
component reliability and then combine the
results in accordance with the system
reliability diagram to determine total system
reliability in its operating environment.
Stress/Strength Analysis -
Structural/Mechanical Analysis of Components
and Systems
Stress/Strength analysis method determines
the probability of failure based on the
probability of stress exceeding strength.
Calculation of Failure Probability
(Unreliability) by:
