ISO TR 29381-2008 PDF

Full title and description

Metallic materials — Measurement of mechanical properties by an instrumented indentation test — Indentation tensile properties. This Technical Report describes approaches to derive tensile properties (true stress–strain curves and derived parameters) from instrumented indentation force–depth data for metallic materials.

Abstract

ISO/TR 29381:2008 summarizes three practicable methods to evaluate indentation-derived tensile properties: representative stress/strain approaches, inverse analysis by finite-element modelling (FEA), and neural‑network based prediction. It sets application ranges aligned with the ISO 14577 classification and recommends an indentation force range approximately from 2 N up to 3 kN; it also discusses the influence of residual stress and provides a reference procedure to evaluate it.

General information

• Status: Published (Technical Report; confirmed at systematic review).
• Publication date: October 2008 (Edition 1, 2008-10).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 77.040.10 (Mechanical testing of metals).
• Edition / version: Edition 1 (2008).
• Number of pages: 29 (ISO published PDF/paper edition).

Scope

Provides methods to obtain tensile behaviour (true stress–strain curves and derived mechanical parameters) of metallic materials from instrumented indentation tests. The document is intended for metallic materials where indentation-based inversion is appropriate and assumes absence (or known evaluation) of residual stresses in the test piece. It addresses practical application limits, recommends an operating force range (approx. 2 N–3 kN) and explains the information and user skills needed for each method.

Key topics and requirements

• Three principal methods to derive tensile properties from indentation data: representative stress/strain, inverse FEA analysis, and neural-network models.
• Input: instrumented indentation force–depth (load–displacement) curves; use of partial unloading cycles to obtain contact stiffness where applicable.
• Recommended indentation force range and alignment with ISO 14577 class ranges (practical focus 2 N to 3 kN in this TR).
• Primary assumption: absence of residual stress in the test piece; includes an informative procedure to evaluate residual stress effects.
• Method-specific requirements: Method 1 for rapid estimates with precomputed models, Method 2 for rigorous inverse FEA with higher computational cost, Method 3 for fast inference after appropriate training data.
• Guidance on data quality, calibration and the user expertise needed for reliable inversion and interpretation.

Typical use and users

Used by materials scientists, metallurgists, research labs, academic groups, quality/production control teams and manufacturers of indentation/test instrumentation who need tensile-property estimates where conventional tensile testing is impractical (e.g., small volumes, coatings, in‑situ components). Also relevant to developers of FEA inversion tools and machine‑learning models for materials characterisation.

Related standards

Closely related to the ISO 14577 series (instrumented indentation test methods and machine verification/calibration) and to conventional tensile test standards (ISO 6892 series) for validation and comparison of tensile-property results. Users commonly apply ISO/TR 29381 results alongside ISO 14577 test-method and calibration practices and compare outcomes to ISO 6892 tensile test data.

Keywords

instrumented indentation; indentation tensile properties; indentation tensile curve; inverse analysis; finite-element analysis; neural network; metallic materials; residual stress; ISO 14577; indentation force–depth.

FAQ

Q: What is this standard?

A: ISO/TR 29381:2008 is a Technical Report that sets out methods to derive tensile properties (true stress–strain curves and related parameters) from instrumented indentation tests on metallic materials.

Q: What does it cover?

A: It describes three methods (representative stress/strain, inverse FEA, neural networks), the input data required (force–depth curves), recommended application ranges (approx. 2 N–3 kN), and addresses the effect and evaluation of residual stress.

Q: Who typically uses it?

A: Materials researchers, test laboratories, instrument manufacturers, and engineers needing tensile-property estimates where sample size, geometry or location make standard tensile tests impractical. It is also used by developers of inversion/ML tools and by quality/control personnel validating small-scale or in-service properties.

Q: Is it current or superseded?

A: The document was published in October 2008 and was last reviewed and confirmed by ISO in 2012; the ISO record indicates this version remains current. Users should, however, check for later related updates to instrumented‑indentation standards (for example updates in the ISO 14577 series) when implementing procedures.

Q: Is it part of a series?

A: It is a Technical Report produced under ISO/TC 164/SC 3 and is intended to be used alongside the ISO 14577 instrumented‑indentation series and conventional tensile‑testing standards (ISO 6892 series) for validation and complementary guidance.

Q: What are the key keywords?

A: Instrumented indentation, indentation tensile properties, force–depth curve, inverse analysis, FEA, neural network, metallic materials, residual stress, ISO 14577.