Hello, I am trying to model spider threads right now, and I have come across an issue where the threads are experiencing large amounts of deformation, requiring a nonlinear stress strain curve.
Here is a sample of how a typical stress-strain curve looks like. You can see it is not exactly straight at larger loads. [image: Representative stress-strain curve of Argiope keyserlingi radial silk showing the key measures of biomechanical properties in spider silks (A. M. T. Harmer, 2010 unpublished data). The biomechanical properties of spider silks (and materials in general) are defined by several key parameters. These include: stress, calculated as force divided by the crosssectional area of the fibre (engineering stress). For silks, this is usually converted to true stress by multiplying engineering stress by L/L 0 (length of stretched fibre/original length; e.g. [79]). This approximates the instantaneous cross-sectional area of the fibre that is important for elastic materials [78]. Strain measures the change in the length of a fibre relative to its original length (engineering strain). It is usually converted to true strain by taking the natural log of L/L 0 [146]. Tensile strength is the stress at the breaking point of a material under uniaxial loading [78]. Extensibility describes the stretchiness of a fibre, for example the percentage increase in a fibre's length at breaking when compared with its original length. Stiffness is defined by Young's modulus and is calculated from the slope of the initial elastic region of the stress-strain curve. It is a measure of the ability of a fibre to resist deformation [95]. Yield is the point where a fibre transitions from elastic (and reversible) deformation to plastic deformation. Higher yield values make fibres more resistant to permanent deformation [33]. Toughness is the energy required to break a thread. It is calculated as the area under the stress-strain curve [95]. Hysteresis (not shown on figure) is the proportion of energy lost during a loading-unloading cycle [78]. The energy required to stretch a silk thread is greater than that required to return it to its natural state as some energy is lost as heat.] I am reading the FEA module documentation and it doesn't seem like there is any information about modelling nonlinear stress strain curves in the FEA module. Is it possible to recreate a stress-strain curve to model this, maybe by adding a few functions inside the FEA module? Thank you, Eugene -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/projectchrono/f76b65c5-48fd-49ff-bf59-9b630f7d4d52n%40googlegroups.com.
