ASTM D6742 Test Fikstürü

Açıklama

ASTM D6742 – Standard Practice for Filled-Hole Tension and Compression Testing of Polymer Matrix Composite Laminates

 

ASTM D6742 provides instructions for modifying open-hole tension and compression test methods to determine filled-hole tensile and compressive strengths.

The composite material forms are limited to continuous-fiber reinforced polymer matrix composites in which the laminate is both symmetric and balanced with

respect to the test direction.

This practice supplements Test Methods ASTM D5766/D5766M (for tension testing) and ASTM D6484/D6484M (for compression testing) with provisions

for testing specimens that contain a close-tolerance fastener or pin installed in the hole.

Several important test specimen parameters (for example, fastener selection, fastener installation method, and fastener hole tolerance) are not mandated by this

practice; however, repeatable results require that these parameters be specified and reported.

---

ASTM D6742  / Significance and Use

This practice provides supplemental instructions that allow Test Methods ASTM D5766/D5766M (for tension testing) and ASTM D6484/D6484M

(for compression testing) to determine filled-hole tensile and compressive strength data for material specifications, research and development, material design

allowables, and quality assurance.

Factors that influence filled-hole tensile and compressive strengths and shall therefore be reported include the following: material, methods of material fabrication,

accuracy of lay-up, laminate stacking sequence and overall thickness, specimen geometry (including hole diameter, diameter-to-thickness ratio,

and width-to-diameter ratio), specimen preparation (especially of the hole), fastener-hole clearance, fastener type, fastener geometry, fastener installation method,

fastener torque (if appropriate), countersink depth (if appropriate), specimen conditioning, environment of testing, specimen alignment and gripping, speed of

testing, time at temperature, void content, and volume percent reinforcement.

Properties that result include the following:

Filled-hole tensile (FHT) strength,

Filled-hole compressive (FHC) strength,

---

ASTM D6742  / Apparatus

General Apparatus—General apparatus shall be in accordance with Test Methods ASTM D5766/D5766M (for tension tests) and ASTM D6484/D6484M

(for compression tests), although with a fastener or pin installed in the specimen hole.

The micrometer or gage used shall be capable of determining the hole and fastener diameters to 68 μm [60.0003 in.].

Fastener—The fastener or pin type shall be specified as an initial test parameter and reported.

The nominal fastener diameter shall be 6 mm [0.25 in.], unless a range of diameters is being investigated.

Some fastener types (for example blind bolts) may not be available in this diameter; for these, it is recommended to use a fastener for which the diameter is as

close as possible to 6 mm [0.25 in.].

The installation torque (if applicable) shall be specified as an initial test parameter and reported.

This value may be a measured torque or a specification torque for fasteners with lock-setting features.

If washers are used, the washer type, number of washers, and washer location(s) shall be specified as initial test parameters and reported.

Reuse of fasteners is not recommended because of potential differences in through-thickness clamp-up for a given torque level, caused by wear of the threads.

---

ASTM D6742  / Summary of Practice

Filled-Hole Tensile Strength—In accordance with Test Method ASTM D5766/D5766M, but with a close-tolerance fastener or pin installed in the hole, perform

a uniaxial tension test of a balanced, symmetric laminate with a centrally located hole.

Filled-Hole Compressive Strength—In accordance with Test Method ASTM D6484/D6484M, but with a close-tolerance fastener or pin installed in the hole,

perform a uniaxial compression test of a balanced, symmetric laminate with a centrally located hole.

*** Before conducting ASTM D6742 , it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.

 

***PARSROS  offers several types of grips and fixtures which will enable you to perform a variety of tests  that

are accurate and repeatable.