PSA D41 1041 Rigid and Semi-Rigid Plastics - Reinforced and Unreinforced Bending

The “PSA D41 1041 Rigid and semi-rigid plastics - Bending, reinforced and unreinforced” standard, developed by the French automotive manufacturer PSA Group (now part of Stellantis), describes the bending properties of rigid and semi-rigid plastics and materials (in the form of rectangular cylinders, in standardized or non-standardized dimensions, obtained by oriented molding or cutting from sheets or other molded forms) with or without reinforcement. This method conforms to the standards “NF EN ISO 14125 Fiber-reinforced plastic composites - Determination of bending properties” and “NF EN ISO 178 Plastics - Determination of bending properties”.

In principle, the test consists of placing a parallelogram cylinder on two supports and deforming it by applying a punch moving at a constant speed at equal distances from the supports. It allows the measurement of one or more of the following properties:

• Bending stress and fracture deflection for materials that fracture before reaching conventional deflection.
• Bending stress for conventional deflection (1,5 times the thickness of the test specimen) for materials that do not fracture before or during conventional deflection.
• Bending stress at minimum load for materials that reach maximum load before or during conventional deflection.
• Bending stress up to fracture or maximum load when conventional deflection is exceeded and required in the material specification.
• The modulus of elasticity observed in bending.

This stress is the maximum theoretical bending stress on the right side of the punch. It is calculated using formulas derived from elasticity theory. When the deformation is not proportional to the applied stress, this stress can differ significantly from the actual stress.

The bending testing machine used in the tests allows for the adjustment of the following test speeds: 0,5 - 1 - 2 - 5 - 10 and 20 mm/min. It displays loads with an error margin not exceeding plus/minus 1% and deflections with an error margin not exceeding plus/minus 2%. The radii of the punches and supports are given in the standard. The supports and punches must be at least equal in size to the dimensions of the test specimens. The distance between the supports must be adjustable. The tests also utilize a climate chamber maintained at a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent.

Test specimens must be representative of the scale being characterized. To ensure this representativeness, it is necessary to determine the baseline characteristics of the population being studied. The selection criteria for the test specimen(s) should be stated in the test report in accordance with standard A10 0156. In case of doubt regarding sampling, PSA should be contacted for guidelines.

Test specimens can be obtained by molding or cutting. In the latter case, it is necessary to ensure that no cracks occur. The dimensions of the specimen are as follows:

• The length must be greater than or equal to 20 times the thickness.
• Width and thickness must comply with the rules specified in the standard.

When dealing with anisotropic materials in terms of thickness (e.g., laminated materials), test specimens are collected such that the bending force to which they are subjected is in the same direction as the direction in which the force would practically be applied to the parts from which the specimens were taken. For anisotropic materials in the plane, specimens should be collected and tested with respect to two perpendicular directions.

The test is performed on at least five specimens. Fractured specimens outside the middle third of the distance between the supports should be discarded.

Samples are packaged for at least 24 hours at a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent. For highly hygroscopic materials or materials where equilibrium with ambient humidity is slow (plant fibers, polyamide materials), the packaging time may be extended up to one week.

The test is performed at a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50% plus/minus 5%. Tests can also be performed at other temperatures in accordance with the specified characteristics. The width of each sample is measured with an accuracy of 0,05 mm and the thickness with an accuracy of 0,05 mm. The distance between the supports is adjusted to be equal to 15 to 17 times the thickness of the sample set (elongation, deviation between end values ​​should be less than 10% of the average value). The distance between the supports is measured with an accuracy of 0,5%. The sample is placed on the support and the punch is lowered 0,5 mm to the middle of the distance between the supports. The punch speed is adjusted to the value closest to the calculated value. Exceptionally, in some special cases of the current control or if the material document dictates it, a higher punch speed (10 mm/min) may be used to prove that the measurement results are not affected (for materials more susceptible to creep, such as thermoset materials).

The load-deflection curve is recorded with magnifications such as the slope of the curve being close to the bisector of the axes, and the following values ​​are observed:

• If the sample breaks, the load and deflection at the moment of fracture.
• If it does not break, the load at conventional deflection or the load and deflection at maximum load.
• The apparent modulus of elasticity is determined by starting from the linear portion at the origin of the load-deflection curve.

The PSA standards in the “D41” series focus on testing methods for materials used in vehicle interiors and components, particularly flexible cellular materials such as foams, rubbers, and porous plastics commonly found in seats, insulation, and upholstery.

Automotive components must withstand years of use, extreme temperatures, humidity, and mechanical stress without failing. The PSA D41 1041 standard and other tests in the “D41” series help prevent problems such as these:

• The seat foam collapses over time.
• Breakdown of insulation and release of particles.
• Tearing or loss of elasticity in upholstery materials.

This standard is considered important for the following reasons:

• Ensures passenger comfort and long-term durability: The flexible foam in seats and upholstery must maintain its shape and support throughout years of use. These tests evaluate how the materials resist permanent deformation (compression permanent deformation), sagging, or loss of elasticity. This prevents common problems such as seat foam collapse, avoiding uncomfortable driving experiences or a decrease in vehicle resale value.
• It contributes to vehicle safety: Interior materials must perform reliably in collisions or extreme conditions. Durable foams help maintain the structural integrity of seat systems, absorb energy, and prevent failures that could affect passenger safety. Compliance with such standards supports broader safety regulations.
• It guarantees quality throughout the supply chain: Companies supplying Stellantis are required to certify their materials according to standards such as PSA D41 1041. This ensures consistency across millions of vehicles, reduces warranty claims, and protects the brand's reputation for reliability.
• It provides protection against environmental and real-world stresses: Automotive foams are exposed to extreme temperatures (minus 40 degrees to plus 80 degrees), humidity, UV rays, and repeated loading. These tests simulate these conditions, predicting performance and preventing premature material degradation (e.g., cracking, tearing, or gas release).

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its customers, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "PSA D41 1041 Rigid and semi-rigid plastics - Reinforced and unreinforced bending" standard.