@article{BhattaraiStaat2018,
  author    = {Bhattarai, Aroj and Staat, Manfred},
  title     = {Computational comparison of different textile implants to correct apical prolapse in females},
  series = {Current Directions in Biomedical Engineering},
  volume    = {4},
  journal   = {Current Directions in Biomedical Engineering},
  number    = {1},
  publisher = {De Gruyter},
  address   = {Berlin},
  doi       = {10.1515/cdbme-2018-0159},
  pages     = {661 -- 664},
  year      = {2018},
  abstract  = {Prosthetic textile implants of different shapes, sizes and polymers are used to correct the apical prolapse after hysterectomy (removal of the uterus). The selection of the implant before or during minimally invasive surgery depends on the patient's anatomical defect, intended function after reconstruction and most importantly the surgeon's preference. Weakness or damage of the supporting tissues during childbirth, menopause or previous pelvic surgeries may put females in higher risk of prolapse. Numerical simulations of reconstructed pelvic floor with weakened tissues and organ supported by textile product models: DynaMesh®-PRS soft, DynaMesh®-PRP soft and DynaMesh®-CESA from FEG Textiletechnik mbH, Germany are compared.},
  language  = {en}
}
@phdthesis{Bhattarai2018,
  author    = {Bhattarai, Aroj},
  title     = {Constitutive modeling of female pelvic floor dysfunctions and reconstructive surgeries using prosthetic mesh implants},
  isbn      = {978-3-9818074-8-6},
  doi       = {10.17185/duepublico/70340},
  pages     = {192 S.},
  year      = {2018},
  language  = {en}
}
@article{BhattaraiStaat2019,
  author    = {Bhattarai, Aroj and Staat, Manfred},
  title     = {A computational study of organ relocation after laparoscopic pectopexy to repair posthysterectomy vaginal vault prolapse},
  series = {Computer Methods in Biomechanics and Biomedical Engineering: Imaging \& Visualization},
  journal   = {Computer Methods in Biomechanics and Biomedical Engineering: Imaging \& Visualization},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {2168-1171},
  doi       = {10.1080/21681163.2019.1670095},
  year      = {2019},
  language  = {en}
}
@article{BhattaraiMayStaatetal.2022,
  author    = {Bhattarai, Aroj and May, Charlotte Anabell and Staat, Manfred and Kowalczyk, Wojciech and Tran, Thanh Ngoc},
  title     = {Layer-specific damage modeling of porcine large intestine under biaxial tension},
  series = {Bioengineering},
  volume    = {9},
  journal   = {Bioengineering},
  number    = {10, Early Access},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2306-5354},
  doi       = {10.3390/bioengineering9100528},
  pages     = {1 -- 17},
  year      = {2022},
  abstract  = {The mechanical behavior of the large intestine beyond the ultimate stress has never been investigated. Stretching beyond the ultimate stress may drastically impair the tissue microstructure, which consequently weakens its healthy state functions of absorption, temporary storage, and transportation for defecation. Due to closely similar microstructure and function with humans, biaxial tensile experiments on the porcine large intestine have been performed in this study. In this paper, we report hyperelastic characterization of the large intestine based on experiments in 102 specimens. We also report the theoretical analysis of the experimental results, including an exponential damage evolution function. The fracture energies and the threshold stresses are set as damage material parameters for the longitudinal muscular, the circumferential muscular and the submucosal collagenous layers. A biaxial tensile simulation of a linear brick element has been performed to validate the applicability of the estimated material parameters. The model successfully simulates the biomechanical response of the large intestine under physiological and non-physiological loads.},
  language  = {en}
}
@article{BhattaraiHorbachStaatetal.2022,
  author    = {Bhattarai, Aroj and Horbach, Andreas and Staat, Manfred and Kowalczyk, Wojciech and Tran, Thanh Ngoc},
  title     = {Virgin passive colon biomechanics and a literature review of active contraction constitutive models},
  series = {Biomechanics},
  volume    = {2},
  journal   = {Biomechanics},
  number    = {2},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2673-7078},
  doi       = {10.3390/biomechanics2020013},
  pages     = {138 -- 157},
  year      = {2022},
  abstract  = {The objective of this paper is to present our findings on the biomechanical aspects of the virgin passive anisotropic hyperelasticity of the porcine colon based on equibiaxial tensile experiments. Firstly, the characterization of the intestine tissues is discussed for a nearly incompressible hyperelastic fiber-reinforced Holzapfel-Gasser-Ogden constitutive model in virgin passive loading conditions. The stability of the evaluated material parameters is checked for the polyconvexity of the adopted strain energy function using positive eigenvalue constraints of the Hessian matrix with MATLAB. The constitutive material description of the intestine with two collagen fibers in the submucosal and muscular layer each has been implemented in the FORTRAN platform of the commercial finite element software LS-DYNA, and two equibiaxial tensile simulations are presented to validate the results with the optical strain images obtained from the experiments. Furthermore, this paper also reviews the existing models of the active smooth muscle cells, but these models have not been computationally studied here. The review part shows that the constitutive models originally developed for the active contraction of skeletal muscle based on Hill's three-element model, Murphy's four-state cross-bridge chemical kinetic model and Huxley's sliding-filament hypothesis, which are mainly used for arteries, are appropriate for numerical contraction numerical analysis of the large intestine.},
  language  = {en}
}