ASTM D2990 is a set of standard test methods used to measure how plastics deform over time under a constant load (creep) and, when applicable, how long they last before failure (creep-rupture). It covers tensile and compressive creep/creep-rupture, and creep in flexure.
Because creep testing can run for long durations and often requires tight temperature control, equipment configuration matters as much as load capacity. If you need help matching grips, fixtures, and environmental control to your material and test plan, you can talk with our team.
ASTM D2990 — Standard Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics
ASTM D2990 is used when you need time-dependent mechanical performance data for plastics under sustained loading. Typical outputs include creep strain versus time, derived creep modulus behavior, and (in creep-rupture testing) time-to-failure at specified stress levels.
The standard allows flexural creep measurements using three-point loading aligned with flexural test practices, and it also permits four-point loading as an option for flexural creep work.
Quick definition
Document type: Standard test methods.
What it measures: Long-term deformation (creep) and failure under constant load (creep-rupture) for plastics in tension, compression, and flexure under specified environmental conditions.
Typical use: Long-term performance characterization, material comparisons, and engineering design data for parts that carry sustained loads.
What this standard covers
ASTM D2990 covers creep and creep-rupture determination for plastics under controlled environmental conditions.
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Tensile creep and creep-rupture: A constant tensile load is applied and strain is tracked over time; creep-rupture adds time-to-failure at selected stress levels.
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Compressive creep and creep-rupture: A constant compressive load is applied and deformation is tracked over time; creep-rupture evaluates time-to-failure where applicable.
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Flexural creep: Creep in bending using three-point loading, with four-point loading permitted as an option.
Important practical note: For some ductile plastics, rupture may not occur in flexure or compression; tension is commonly preferred for creep-rupture work.
Why this standard matters in testing
Short-term strength and modulus data do not always predict how a plastic part will behave under sustained load for weeks, months, or longer. ASTM D2990 supports decisions where time-dependent deformation and dimensional stability matter, such as parts that must hold shape, maintain alignment, or carry static loads at ambient or elevated temperature.
For product development and QA/QC, creep and creep-rupture data are commonly used to compare candidate materials, set design allowables, and evaluate long-term risk for deformation or failure under service-like loading.
Common materials, product types, or applications covered
ASTM D2990 applies broadly to plastics where long-term loading can cause gradual deformation or time-dependent loss of function. Typical use cases include:
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Structural plastic components: brackets, clips, housings, or supports that carry sustained stress.
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Polymer parts exposed to heat: assemblies where elevated temperature can accelerate creep.
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Design validation: screening materials or confirming a design margin for long-life applications.
Actual specimen type, conditioning, and test conditions are often driven by a material or product specification, purchase requirement, or engineering test plan.
Common test or verification workflow
Most ASTM D2990 programs follow a time-based workflow that prioritizes stable loading and stable environment.
Common workflow steps: define stress level(s) and temperature/conditioning requirements, prepare specimens, apply a constant load in the required mode (tension, compression, or flexure), record deformation versus time over the planned duration, and (when running creep-rupture) continue the test until failure or until a defined endpoint is reached.
What drives setup choices: target test duration, allowable strain measurement uncertainty, number of stations (throughput), environmental temperature range, and whether the goal is creep strain behavior, creep modulus behavior, and/or time-to-rupture.
Equipment commonly used for this standard
ASTM D2990 testing is commonly implemented on dedicated creep frames or creep-rupture systems designed for long-duration constant-load operation.
Typical equipment families: deadweight or lever-arm creep frames; constant-load creep-rupture machines; multi-station creep racks for higher throughput; and test fixtures for tensile, compression, and flexural loading.
Common supporting components: environmental chambers or temperature-controlled enclosures; long-duration displacement/strain measurement (appropriate extensometry or displacement sensors for the loading mode); stable load application hardware; and data acquisition configured for long test timelines.
Equipment selection caution: The most frequent performance issues in creep testing are load stability and temperature uniformity over time. When quoting a system, it helps to define the target temperature range, number of parallel stations, expected maximum strain, and how the lab wants to measure deformation (direct strain on the specimen versus crosshead/fixture displacement).
If you are configuring a creep or creep-rupture setup for plastics—especially with environmental control or multi-station throughput—you can request a detailed quote for an equipment package aligned to your duration, temperature, and measurement needs.
How to read this designation or revision
ASTM standards are commonly cited with a base designation and a revision/reapproval indicator. For this document, you may see citations such as ASTM D2990 with an added suffix (for example, an older revision year and a later reapproval marker).
Revision sensitivity: Creep testing is highly condition-dependent, so the exact cited edition can matter for allowable options (such as flexural loading configuration), definitions, and reporting expectations. When compliance is required, match the customer or contract citation to the exact ASTM D2990 edition used in the lab.
Related standards, methods, or frameworks
ASTM D2990 is often used alongside other mechanical property standards and flexural loading practices, depending on whether the program is focused on tensile, compressive, or flexural behavior.
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Flexural loading practice references: Three-point flexural loading is aligned with common flexural test practices, and four-point loading may be used as an option for flexural creep programs.
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ISO comparison note: ISO 899 Parts 1 and 2 address similar subject matter, but methods and results are not directly interchangeable; ISO 899 Part 1 addresses tensile creep/creep-to-rupture and ISO 899 Part 2 addresses flexural creep.
Get help selecting a creep testing setup for ASTM D2990
If you are planning ASTM D2990 testing and want to confirm the right loading mode fixtures (tension, compression, 3-point, or 4-point), station count, or temperature-control approach, contact our team to discuss your material, duration, and reporting requirements.