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  1. Article ; Online: The simulation of mechanical responses of nonwoven fabrics using an improved meshless discrete algorithm

    Jirsák, Oldrich / Henyš, Petr / Pokorný, Pavel

    The Journal of The Textile Institute. 2023 Apr. 3, v. 114, no. 4 p.542-551

    2023  

    Abstract: The structures of nonwoven fabrics are geometrically complex and random; therefore, optimising them in terms of performance, both in the production process and from a functionality perspective, is an engineering challenge. This paper introduces a ... ...

    Abstract The structures of nonwoven fabrics are geometrically complex and random; therefore, optimising them in terms of performance, both in the production process and from a functionality perspective, is an engineering challenge. This paper introduces a computational approach to simulate mechanical responses of nonwoven fabrics under uniaxial displacement controlled loads. The proposed method enables us to simulate the evolution of multiple-fibre damage and the spatial randomness of the geometrical and material properties of nonwoven structures. These effects are critical for successful computational design and optimisation of such nonwoven structures. The algorithm was tested in several numerical examples, and we performed an extensive parametric study.
    Keywords algorithms ; evolution ; fabrics ; Nonwoven fabric ; mechanical response ; meshless method ; fibre damage
    Language English
    Dates of publication 2023-0403
    Size p. 542-551.
    Publishing place Taylor & Francis
    Document type Article ; Online
    ISSN 1754-2340
    DOI 10.1080/00405000.2022.2052451
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: Individual yarn fibre extraction from micro-CT: multilevel machine learning approach

    Henyš, Petr / Čapek, Lukáš

    The journal of the Textile Institute. 2021 Dec. 2, v. 112, no. 12

    2021  

    Abstract: The internal structure and mechanics of the fibre materials, such as yarn or woven textile, are highly complex. Exploring the fibre structure is an essential step in material engineering either from the experimental or computational point of view. In ... ...

    Abstract The internal structure and mechanics of the fibre materials, such as yarn or woven textile, are highly complex. Exploring the fibre structure is an essential step in material engineering either from the experimental or computational point of view. In this study, a new method to extract geometrical and morphological parameters of fibre structures is proposed. The method benefits from standard image analysis and machine learning technique to efficiently extract fibre segments from microcomputer tomography data. The proposed algorithm is tested on the yarn and woven textile materials with different resolution and quality. The developed method can extract the individual fibres with varying accuracy from 73% to 100% with processing time 2–5 s on the tested samples.
    Keywords algorithms ; image analysis ; mechanics ; micro-computed tomography ; woven fabrics
    Language English
    Dates of publication 2021-1202
    Size p. 1979-1985.
    Publishing place Taylor & Francis
    Document type Article
    ISSN 1754-2340
    DOI 10.1080/00405000.2020.1865503
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Evaluating the stability of external fixators following pelvic injury: A systematic review of biomechanical testing methods.

    Meuser, Annika Hela / Henyš, Petr / Höch, Andreas / Gänsslen, Axel / Hammer, Niels

    Journal of the mechanical behavior of biomedical materials

    2024  Volume 153, Page(s) 106488

    Abstract: Introduction: This systematic review aims to identify previously used techniques in biomechanics to assess pelvic instability following pelvic injury, focusing on external fixation constructs.: Methods: A systematic literature search was conducted to ...

    Abstract Introduction: This systematic review aims to identify previously used techniques in biomechanics to assess pelvic instability following pelvic injury, focusing on external fixation constructs.
    Methods: A systematic literature search was conducted to include biomechanical studies and to exclude clinical trials.
    Results: Of an initial 4666 studies found, 38 met the inclusion criteria. 84% of the included studies were retrieved from PubMed, Scopus, and Web of Science. The studies analysed 106 postmortem specimens, 154 synthetic bones, and 103 computational models. Most specimens were male (97% synthetic, 70% postmortem specimens). Both the type of injury and the classification system employed varied across studies. About 82% of the injuries assessed were of type C. Two different fixators were tested for FFPII and type A injury, five for type B injury, and fifteen for type C injury. Large variability was observed for external fixation constructs concerning device type and configuration, pin size, and geometry. Biomechanical studies deployed various methods to assess injury displacement, deformation, stiffness, and motion. Thereby, loading protocols differed and inconsistent definitions of failure were determined. Measurement techniques applied in biomechanical test setups included strain gauges, force transducers, and motion tracking techniques.
    Discussion and conclusion: An ideal fixation method should be safe, stable, non-obstructive, and have low complication rates. Although biomechanical testing should ensure that the load applied during testing is representative of a physiological load, a high degree of variability was found in the current literature in both the loading and measurement equipment. The lack of a standardised test design for fixation constructs in pelvic injuries across the studies challenges comparisons between them. When interpreting the results of biomechanical studies, it seems crucial to consider the limitations in cross-study comparability, with implications on their applicability to the clinical setting.
    MeSH term(s) Humans ; Biomechanical Phenomena ; External Fixators ; Fracture Fixation/methods ; Fractures, Bone ; Pelvic Bones/surgery
    Language English
    Publishing date 2024-02-29
    Publishing country Netherlands
    Document type Journal Article ; Systematic Review
    ZDB-ID 2378381-3
    ISSN 1878-0180 ; 1751-6161
    ISSN (online) 1878-0180
    ISSN 1751-6161
    DOI 10.1016/j.jmbbm.2024.106488
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  4. Article ; Online: From computed tomography to finite element space: A unified bone material mapping strategy.

    Henyš, Petr / Vořechovský, Miroslav / Stebel, Jan / Kuchař, Michal / Exner, Pavel

    Clinical biomechanics (Bristol, Avon)

    2022  Volume 97, Page(s) 105704

    Abstract: Background: The spatially varying mechanical properties in finite element models of bone are most often derived from bone density data obtained via quantitative computed tomography. The key step is to accurately and efficiently map the density given in ... ...

    Abstract Background: The spatially varying mechanical properties in finite element models of bone are most often derived from bone density data obtained via quantitative computed tomography. The key step is to accurately and efficiently map the density given in voxels to the finite element mesh.
    Methods: The density projection is first formulated in least-squares terms and then discretized using a continuous and discontinuous variant of the finite element method. Both discretization variants are compared with the nodal and element approaches known from the literature.
    Findings: In terms of accuracy in the L2 norm, energy distance and efficiency, the discontinuous zero-order variant appears to be the most advantageous. The proposed variant sufficiently preserves the spectrum of density at the edges, while keeping computational cost low.
    Interpretation: The continuous finite element method is analogous to the nodal formulation in the literature, while the discontinuous finite element method is analogous to the element formulation. The two variants differ in terms of implementation, computational cost and ability to preserve the density spectrum. These differences cannot be described and measured by known indirect methods from the literature.
    MeSH term(s) Bone Density ; Bone and Bones/diagnostic imaging ; Finite Element Analysis ; Humans ; Tomography, X-Ray Computed/methods
    Language English
    Publishing date 2022-06-15
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 632747-3
    ISSN 1879-1271 ; 0268-0033
    ISSN (online) 1879-1271
    ISSN 0268-0033
    DOI 10.1016/j.clinbiomech.2022.105704
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  5. Article ; Online: Mechanical metric for skeletal biomechanics derived from spectral analysis of stiffness matrix.

    Henyš, Petr / Kuchař, Michal / Hájek, Petr / Hammer, Niels

    Scientific reports

    2021  Volume 11, Issue 1, Page(s) 15690

    Abstract: A new metric for the quantitative and qualitative evaluation of bone stiffness is introduced. It is based on the spectral decomposition of stiffness matrix computed with finite element method. The here proposed metric is defined as an amplitude rescaled ... ...

    Abstract A new metric for the quantitative and qualitative evaluation of bone stiffness is introduced. It is based on the spectral decomposition of stiffness matrix computed with finite element method. The here proposed metric is defined as an amplitude rescaled eigenvalues of stiffness matrix. The metric contains unique information on the principal stiffness of bone and reflects both bone shape and material properties. The metric was compared with anthropometrical measures and was tested for sex sensitivity on pelvis bone. Further, the smallest stiffness of pelvis was computed under a certain loading condition and analyzed with respect to sex and direction. The metric complements anthropometrical measures and provides a unique information about the smallest bone stiffness independent from the loading configuration and can be easily computed by state-of-the-art subject specified finite element algorithms.
    MeSH term(s) Algorithms ; Biomechanical Phenomena ; Biophysics ; Bone and Bones ; Female ; Finite Element Analysis ; Humans ; Male ; Mechanical Phenomena ; Models, Theoretical ; Spectrum Analysis/methods
    Language English
    Publishing date 2021-08-03
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-021-94998-5
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Computational modal analysis of a composite pelvic bone: convergence and validation studies.

    Henyš, Petr / Čapek, Lukáš

    Computer methods in biomechanics and biomedical engineering

    2019  Volume 22, Issue 9, Page(s) 916–924

    Abstract: The purpose of the present study was to describe the structural density and geometry of the bone, as well as its sensitivity to the resolution of finite element discretisation. The study introduces a novel way to validate biomechanical model of the bone ... ...

    Abstract The purpose of the present study was to describe the structural density and geometry of the bone, as well as its sensitivity to the resolution of finite element discretisation. The study introduces a novel way to validate biomechanical model of the bone by experimental modal analysis. The structural density and geometry of the model was obtained from a composite bone. A detailed investigation of the weight dependence of the bone on the mesh resolution was performed to obtain the best match with the real weight of the tested bone. The computational model was compared with the experimental results obtained from the modal analysis. The overall changes of the modal properties and bone weight in the model caused by different mesh resolutions and order of approximation were below 10%, despite the bone was modelled with simple isotropic material properties. The experimental modal analysis shows a great potential to be a robust verification tool of computational biomechanical models because it provides boundary conditions-free results. The sensitivity analysis revealed that the linear approximation of the density field is not suitable for the modelling of the modal response of composite bone.
    MeSH term(s) Biomechanical Phenomena ; Computer Simulation ; Finite Element Analysis ; Humans ; Linear Models ; Organ Size ; Pelvic Bones/anatomy & histology ; Pelvic Bones/diagnostic imaging ; Reproducibility of Results ; Stress, Mechanical ; Tomography, X-Ray Computed
    Language English
    Publishing date 2019-04-19
    Publishing country England
    Document type Journal Article ; Validation Studies
    ZDB-ID 2071764-7
    ISSN 1476-8259 ; 1025-5842
    ISSN (online) 1476-8259
    ISSN 1025-5842
    DOI 10.1080/10255842.2019.1604949
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  7. Article: Shape or size matters? Towards standard reporting of tensile testing parameters for human soft tissues: systematic review and finite element analysis.

    Lin, Alvin C / Pirrung, Felix / Niestrawska, Justyna A / Ondruschka, Benjamin / Pinter, Gerald / Henyš, Petr / Hammer, Niels

    Frontiers in bioengineering and biotechnology

    2024  Volume 12, Page(s) 1368383

    Abstract: Material properties of soft-tissue samples are often derived through uniaxial tensile testing. For engineering materials, testing parameters (e.g., sample geometries and clamping conditions) are described by international standards; for biological ... ...

    Abstract Material properties of soft-tissue samples are often derived through uniaxial tensile testing. For engineering materials, testing parameters (e.g., sample geometries and clamping conditions) are described by international standards; for biological tissues, such standards do not exist. To investigate what testing parameters have been reported for tensile testing of human soft-tissue samples, a systematic review of the literature was performed using PRISMA guidelines. Soft tissues are described as anisotropic and/or hyperelastic. Thus, we explored how the retrieved parameters compared against standards for engineering materials of similar characteristics. All research articles published in English, with an Abstract, and before 1 January 2023 were retrieved from databases of
    Language English
    Publishing date 2024-03-26
    Publishing country Switzerland
    Document type Systematic Review
    ZDB-ID 2719493-0
    ISSN 2296-4185
    ISSN 2296-4185
    DOI 10.3389/fbioe.2024.1368383
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  8. Article ; Online: The opening size of the laminoplasty is dependent on the groove size: A numerical study.

    Hradil, Jan / Horak, Zdenek / Henys, Petr / Capek, Lukas

    Clinical biomechanics (Bristol, Avon)

    2021  Volume 89, Page(s) 105479

    Abstract: Background: The expansion of the cervical vertebrae lamina appears to be crucial to related surgical procedures. The dimensions of the groove influence the strain concentration within the lamina of the vertebra and, thus, the potential success or ... ...

    Abstract Background: The expansion of the cervical vertebrae lamina appears to be crucial to related surgical procedures. The dimensions of the groove influence the strain concentration within the lamina of the vertebra and, thus, the potential success or failure of respective surgical procedure. The aim of this computational study is to clarify both the role of the size of the groove with concern to both the open door and the double door laminoplasty techniques.
    Methods: Finite element models were created via computer tomography with varying lamina groove dimensions. Displacements were applied to the models at the open side of the vertebral arch and the vertebral body was constrained prior to movement along all the axes. The maximal opening size measured on the inner side of the lamina and the percentage increase in the initial spinal areas were subsequently analyzed.
    Findings: The elastic strain concentration value was observed for the groove in all cases, while the maximal principal elastic strain concentration value was observed at the opposite side to the groove cut into the lamina, also in all cases. The maximal area increase related to the 4 mm groove accompanied by the preservation of the ventral cortex of the bone.
    Interpretation: The study suggested three conclusions a) the wider the groove, the greater is the opening potential, b) the maximal opening size following laminoplasty is not dependent on the depth of the bone cut for this type of groove, c) no benefit accrues in terms of the opening size following the cutting of a supplementary groove at the beginning of the lamina.
    MeSH term(s) Cervical Vertebrae/diagnostic imaging ; Cervical Vertebrae/surgery ; Humans ; Laminoplasty ; Retrospective Studies ; Tomography, X-Ray Computed ; Treatment Outcome
    Language English
    Publishing date 2021-09-11
    Publishing country England
    Document type Journal Article
    ZDB-ID 632747-3
    ISSN 1879-1271 ; 0268-0033
    ISSN (online) 1879-1271
    ISSN 0268-0033
    DOI 10.1016/j.clinbiomech.2021.105479
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  9. Article ; Online: Shape morphing technique can accurately predict pelvic bone landmarks.

    Kuchař, Michal / Henyš, Petr / Rejtar, Pavel / Hájek, Petr

    International journal of legal medicine

    2021  Volume 135, Issue 4, Page(s) 1617–1626

    Abstract: Diffeomorphic shape registration allows for the seamless geometric alignment of shapes. In this study, we demonstrated the use of a registration algorithm to automatically seed anthropological landmarks on the CT images of the pelvis. We found a high ... ...

    Abstract Diffeomorphic shape registration allows for the seamless geometric alignment of shapes. In this study, we demonstrated the use of a registration algorithm to automatically seed anthropological landmarks on the CT images of the pelvis. We found a high correlation between manually and automatically seeded landmarks. The registration algorithm makes it possible to achieve a high degree of automation with the potential to reduce operator errors in the seeding of anthropological landmarks. The results of this study represent a promising step forward in effectively defining the anthropological measures of the human skeleton.
    MeSH term(s) Aged ; Algorithms ; Anatomic Landmarks ; Female ; Forensic Anthropology/methods ; Humans ; Image Processing, Computer-Assisted ; Male ; Middle Aged ; Pelvic Bones/anatomy & histology ; Pelvic Bones/diagnostic imaging ; Sex Determination by Skeleton/methods ; Tomography, X-Ray Computed
    Language English
    Publishing date 2021-01-27
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1055109-8
    ISSN 1437-1596 ; 0937-9827
    ISSN (online) 1437-1596
    ISSN 0937-9827
    DOI 10.1007/s00414-021-02501-6
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    Un I Zs.312: Show issues Location:
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  10. Article ; Online: Impact Force, Polar Gap and Modal Parameters Predict Acetabular Cup Fixation: A Study on a Composite Bone.

    Henyš, Petr / Čapek, Lukáš

    Annals of biomedical engineering

    2018  Volume 46, Issue 4, Page(s) 590–604

    Abstract: The balanced initial fixation of an implant makes up a crucial condition for its long-term survival. However, the quantification of initial fixation is no easy task and, to date, only qualitative assessments can be made. Although the concept of measuring ...

    Abstract The balanced initial fixation of an implant makes up a crucial condition for its long-term survival. However, the quantification of initial fixation is no easy task and, to date, only qualitative assessments can be made. Although the concept of measuring fixation by means of vibration analysis is already widely used in dental implantology, the rigorous application of this method for the assessment of the fixation of femoral and acetabular components remains a challenge. Moreover, most studies on this subject have tended to focus solely on the femoral stem even though acetabular cup fixation is also important and even more difficult with respect to qualitative measurement. This study describes a comprehensive experiment aimed at assessing acetabular cup fixation. Fixation is expressed in terms of the impact force and polar gap variables, which are correlated with the modal properties of the acetabular implant during the various insertion stages. The predictive capabilities of modal frequencies and frequency functions were investigated by means of surrogate models based on the Gaussian process and functional principal component analysis. The prediction accuracy of the proposed models was in the range 82-94%. The results indicate that natural frequencies, reduced frequency, impact force and polar gap features provide great potential in terms of the prediction of implant fixation.
    MeSH term(s) Female ; Femur Head/pathology ; Femur Head/physiopathology ; Fracture Fixation, Internal ; Humans ; Internal Fixators ; Male ; Models, Biological ; Pelvic Bones/pathology ; Pelvic Bones/physiopathology ; Vibration
    Language English
    Publishing date 2018-01-16
    Publishing country United States
    Document type Journal Article
    ZDB-ID 185984-5
    ISSN 1573-9686 ; 0191-5649 ; 0090-6964
    ISSN (online) 1573-9686
    ISSN 0191-5649 ; 0090-6964
    DOI 10.1007/s10439-018-1980-3
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