Apple viscoelastic complex model for bruise damage analysis in constant velocity grasping by gripper.

• A complex model used to estimate apple stress according to grasping speed is proposed. • The apple 3D layered finite element model with viscoelastic property is established. • Dynamic grasping process with characteristics of speed and energy input is simulated. • Apple skin will be more vulnerable than other tissues above grasping speed of 3 mm/s. This study focuses on establishing apple viscoelastic finite element complex model to estimate apple stress variation during grasping with its own characteristics of constant velocity and continuous energy input. The deformation resistance of apple is calculated by MATLAB based on apple viscoelastic Burgers model and stage dynamic characteristics of grasping process, and used for defining the load function in ANSYS. Then, the layered solid model consisted by skin, flesh, core of apple is established in ANSYS and simulation carries out. Solution results of designed model show that maximum equivalent stress and maximum deformation of apple are 0.42 MPa and 0.72 mm respectively at grasping velocity of 3 mm/s, after that apple skin starts to have grasping damage prior to the flesh and core of apple due to plastic deformation occurring. Lastly, the actual experiment to verify the reliability of designed model was carried out. This study proposes an effective complex model to estimate apple stress from the perspective of grasping velocity by general finite element software. [ABSTRACT FROM AUTHOR]