ASTM D1184 Flexural Strength of Adhesive Bonded Laminated Assemblies

Scope:

The ASTM D1184 test method is a standard test method for determining the flexural strength of adhesive bonded laminated assemblies when subjected to flexural stresses with standard form specimens and under defined pretreatment, temperature, relative humidity, and testing methodology conditions. 

Rather than reducing shear stress to a minimum, the test specimen and testing technique used in the ASTM D1184 test method was designed to create a considerable portion of shear forces between the laminae of the test piece when the load is applied. This test method is suitable for both wood and metal bonded specimens, and it also allows you to compare the flexural properties of different assemblies. The ASTM D1184 standard also aids in the reduction of data of metal and wood specimens to a comparable basis through the use of standard formulas.

Procedure:

The specimen tested by ASTM D1184 is a basic beam made up of eight bonded plies loaded at the mid-span. The specimen is examined under standard temperature and humidity conditions.  Then, using conventional formulas, the flexural characteristics of metal and wood specimens are compared. 

Video 01: Wood bending strength test

Specimen size:

The ASTM D1184 test method requires two categories of specimens:

➢ Wood specimens 
➢ Metal specimens 

These specimens are rectangular pieces with a length of 38 mm and a width of 19.1 mm.

Data:

The following formulae are used in ASTM D1184 test method:

❖ For metal specimens the data is reduced to a comparable basis by means of the maximum  shear stress formula, as follows:

S_s = 3P/4bd 

where, 

S_s = maximum shear stress 

P = breaking load 

B = width of the beam 

D = depth of the beam 

❖ For wood specimens, the data is reduced to a comparable basis by means of the flexural  strength formula, as follows: 

S = 3PL/2bd²  

where, 

S = flexural strength 

P = breaking load 

L = distance between supports 

B = width of the beam 

D = depth of the beam

Conclusion:

The ASTM D1184 test method is a standard test method for determining the flexural strength of adhesive bonded laminated assemblies when subjected to flexural stresses with standard form specimens and under defined pretreatment, temperature, relative humidity, and testing methodology conditions.