Tube deflection test
Proving how shaped tubing offers increased strength performance
As a leading stainless steel tube manufacturer, it is important for us to stand by the quality of all the tube profiles that we supply and the tube deflection test is one way we ensure that you get the best product – every time. Every tube profile that we manufacture goes through an intensive and extensive development phase to ensure the integrity of each of our finished tubes. This comprehensive process is undertaken for each size of each profile shape. We are continuously developing new tube products to add to our extensive standard range, and as such we conduct a variety of tests.
In this particular test, we are looking at the resistance to bending for each of our tube profiles; Flat-sided Oval Tube, Oval Tube, Radius Square Tube, Twisted Square Tube and D-shaped Tube. A standard stainless steel round tube, which is how all of our tube profile products begin, was used as a control sample. This experiment would enable us to see whether the individual profile shapes had any bearing on the strength and integrity of the tubes when compared to the standard round tube.
The deflection test method
The test was performed identically for each of the stainless steel 316L tube profiles. A length of stainless steel tube, 1 metre long, was securely held in place at each end. A downward force (called a normal force, as it is perpendicular to the surface) was then applied to the midpoint of the tube length over a contact area of 50mm.
The same amount of force was used in every experiment to test each individual tube profile. This force was the equivalent of 400kg (882lbs), which is the same as a male coastal grizzly bear. The force was applied through the contact area at the midpoint of the stainless steel tube and in a downward direction, perpendicular to the stainless steel tube, causing the steel tube to bend in the direction of the force. The deflection of the tube (the distance moved) was measured and recorded.
During the test, the stainless steel tube profile material is loaded with the contact force to produce stress which causes the material (inox steel) to deform or as it is often referred to as strain. Strain is the relative change in shape of an object when external forces are applied. Hooke’s law states that the strain in a solid is proportional to the applied stress (force) within the elastic limit of that solid.
Each tube profile was tested in an identical manner to ensure accurate results were recorded. These deflection tests have been officially adjudicated by Able Lifting Equipment (Southern) Ltd. If you would like to know more information on the method used during these tests then please contact us today.
To begin the test, and set a benchmark to compare with the various stainless steel tube profile shapes, we took a standard round stainless steel tube. The round tube dimensions were 38.1mm OD (Outside Diameter) x 1.5mm wall thickness. The 1 metre length of circular stainless steel tube was securely fastened into position ready to have the force applied.
After withstanding the 400kg force, the measured deflection of the stainless steel round tube was 10.2mm. This measurement was then used as the benchmark to compare with each stainless steel tube profile shape.
Square Tube (flush)
The dimensions of the Radius Square tube were 33mm Width x 33mm Height x 1.5mm Wall Thickness. The measured deflection of the square tube profile when flush was 4.7mm.
Square Tube (45º)
The dimensions of the Radius Square tube were 33mm Width x 33mm Height x 1.5mm Wall Thickness. The measured deflection of the Square Tube profile when on an angle was 5.7mm.
Twisted Square Tube
The dimensions of the Twisted Square tube were 33mm Width x 33mm Height x 1.5mm Wall Thickness. The measured deflection of the Twisted Square tube profile was 8.2mm.
The dimensions of the D-shaped tube were 50mm Width x 18mm Height x 1.5mm Wall Thickness. The measured deflection of the D-shaped tube profile was 5.2mm.
Flat-Sided Oval Tube
The dimensions of the Flat-sided Oval tube were 48mm Width x 21mm Height x 1.5mm Wall Thickness. The measured deflection of the Flat-sided Oval tube profile was 4.7mm.
The dimension of the Oval tube were 47mm Width x 25mm Height x 1.5mm Wall Thickness. The measured deflection of the Oval tube profile was 5.7mm.
The experiment conducted here provides us with evidence that the profile shapes that Timeless Tube manufacture enhance the strength of the tube when compared to the original stainless steel round tube.
The results gathered from our methodical experiment show how each tube profile has increased in strength by between 20% – 54%. Buckling occurred in the profile designs of irregular shapes when the force was applied to the larger dimension of the profile, i.e. on the flat side. Although not an exhaustive test, we have still seen a strong indication of how forming a stainless steel tube profile can increase its strength.
This demonstrates that by forming our stainless steel tubes, they are therefore not only more practical and aesthetically pleasing but have the added benefit of increased strength performance. This additional performance allows our stainless steel tube profiles to be used in a wider scope of applications compared to standard round tube.
Do you have a project that needs extra strength from stainless steel tubes then get in contact with Timeless Tube today!