24.09.2024 by Dr. Wiebold Wurpts
Lost your earplugs? NETZSCH may know why!
Sometimes, your hotel turns out – contrary to the description – to be right on a busy road; or your neighbor doesn't turn down their music at night; or you simply have some noisy business of your own. This is when earplugs can help – if they stay in place.
Sometimes, your hotel turns out – contrary to the description – to be right on a busy road; or your neighbor doesn't turn down their music at night; or you simply have some noisy business of your own. This is when earplugs can help – if they stay in place.
To ensure a tight fit, the earplugs are first squeezed and then inserted into the ear. There, they seal the ear canal and dampen the ambient noise. Unfortunately, the contact pressure in the earplugs reduces over time and, if you are unlucky, they will fall out again after a while.
Earplugs are made of viscoelastic foam so that they dampen noise. If this is compressed, the pressure in the material is reduced over time. This is known as StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation. To simulate this behavior, a 9-mm-long piece was cut out of an earplug and examined in the NETZSCH DMA 303 Eplexor®. The sample was heated to the human body temperature of 36°C and then subjected to a StrainStrain describes a deformation of a material, which is loaded mechanically by an external force or stress. Rubber compounds show creep properties, if a static load is applied.strain of 30%.
As usual, compression forces are noted in the diagram with a negative sign. The maximum force of 1.147 N is reached shortly after the StrainStrain describes a deformation of a material, which is loaded mechanically by an external force or stress. Rubber compounds show creep properties, if a static load is applied.strain is applied. The force then reduces to 0.888 N after 30 min, which is a reduction of 22%. As usual with RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation processes, this process does not take place evenly over time, but rather exponentially. Accordingly, the earplug already loses 21% of its pre-StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress in the first 15 min, and then only 1% of its pre-StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress in the following 15 min.
In other words: If the earplug is still in place after 15 minutes, it will no longer fall out.
