TY  - JOUR
AU  - Aleksendrić, D.
AU  - Balać, Igor
AU  - Tang, Chak Yin
AU  - Tsui, C. P.
AU  - Uskoković, Petar S.
AU  - Uskoković, Dragan
PY  - 2010
UR  - https://dais.sanu.ac.rs/123456789/3432
AB  - In this paper, the mechanical properties of polymer matrix phase (modulus of elasticity, yield stress and work hardening rate) have been determined using combined methods such as nanoindentation, finite element modelling and artificial neural networks. The approach of neural modelling has been employed for the functional approximation of the nanoindentation load-displacement curves. The data obtained from finite element analyses have been used for the artificial neural networks training and validating. The neural model of polymer matrix phase of poly-l-lactide (PLLA) polymer in hydroxyapatite (HAp)/PLLA mechanical behaviour has been developed and tested versus unknown data related to the load-displacement curves that were not used during the neural network training. Based on this neural model, the nanoindentation matrix phase properties of PLLA polymer in HAp/PLLA composite have been predicted. © 2010 Institute of Materials, Minerals and Mining.
PB  - Maney Publishing
T2  - Advances in Applied Ceramics
T1  - Surface characterisation of PLLA polymer in HAp/PLLA biocomposite material by means of nanoindentation and artificial neural networks
SP  - 65
EP  - 70
VL  - 109
IS  - 2
DO  - 10.1179/174367509X12502621261613
UR  - https://hdl.handle.net/21.15107/rcub_dais_3432
ER  - 

@article{
author = "Aleksendrić, D. and Balać, Igor and Tang, Chak Yin and Tsui, C. P. and Uskoković, Petar S. and Uskoković, Dragan",
year = "2010",
abstract = "In this paper, the mechanical properties of polymer matrix phase (modulus of elasticity, yield stress and work hardening rate) have been determined using combined methods such as nanoindentation, finite element modelling and artificial neural networks. The approach of neural modelling has been employed for the functional approximation of the nanoindentation load-displacement curves. The data obtained from finite element analyses have been used for the artificial neural networks training and validating. The neural model of polymer matrix phase of poly-l-lactide (PLLA) polymer in hydroxyapatite (HAp)/PLLA mechanical behaviour has been developed and tested versus unknown data related to the load-displacement curves that were not used during the neural network training. Based on this neural model, the nanoindentation matrix phase properties of PLLA polymer in HAp/PLLA composite have been predicted. © 2010 Institute of Materials, Minerals and Mining.",
publisher = "Maney Publishing",
journal = "Advances in Applied Ceramics",
title = "Surface characterisation of PLLA polymer in HAp/PLLA biocomposite material by means of nanoindentation and artificial neural networks",
pages = "65-70",
volume = "109",
number = "2",
doi = "10.1179/174367509X12502621261613",
url = "https://hdl.handle.net/21.15107/rcub_dais_3432"
}

Aleksendrić, D., Balać, I., Tang, C. Y., Tsui, C. P., Uskoković, P. S.,& Uskoković, D.. (2010). Surface characterisation of PLLA polymer in HAp/PLLA biocomposite material by means of nanoindentation and artificial neural networks. in Advances in Applied Ceramics
Maney Publishing., 109(2), 65-70.
https://doi.org/10.1179/174367509X12502621261613
https://hdl.handle.net/21.15107/rcub_dais_3432

Aleksendrić D, Balać I, Tang CY, Tsui CP, Uskoković PS, Uskoković D. Surface characterisation of PLLA polymer in HAp/PLLA biocomposite material by means of nanoindentation and artificial neural networks. in Advances in Applied Ceramics. 2010;109(2):65-70.
doi:10.1179/174367509X12502621261613
https://hdl.handle.net/21.15107/rcub_dais_3432 .

Aleksendrić, D., Balać, Igor, Tang, Chak Yin, Tsui, C. P., Uskoković, Petar S., Uskoković, Dragan, "Surface characterisation of PLLA polymer in HAp/PLLA biocomposite material by means of nanoindentation and artificial neural networks" in Advances in Applied Ceramics, 109, no. 2 (2010):65-70,
https://doi.org/10.1179/174367509X12502621261613 .,
https://hdl.handle.net/21.15107/rcub_dais_3432 .

TY  - JOUR
AU  - Uskoković, Petar
AU  - Tang, Chak Yin
AU  - Tsui, C. P.
AU  - Ignjatović, Nenad
AU  - Uskoković, Dragan
PY  - 2007
UR  - https://dais.sanu.ac.rs/123456789/14360
AB  - Biocomposites with ceramic fillers and polymer matrix are becoming attractive materials for bone tissue replacements. Nanoindentation has been used to locally characterize the surface mechanical properties of the hydroxyapatite/pOly-L-lactide (HAp/PLLA) biocomposite. Additionally, differences in the mechanical properties of HAP phase were successfully characterized as a function of surface morphology by using a highresolution modulus mapping technique. HAP granules consist of agglomerates of grainy clusters. Mechanical properties of ceramic grains and PLLA are in fair agreement with literature data. High-resolution methods were able to measure the properties of boundary phases between grains and the pore regions between particles in the agglomerate. After short-time immersion in distilled water, material surface showed a large decrease in storage modulus.
PB  - Oxford : Elsevier Sci Ltd.
T2  - Journal of the European Ceramic Society
T1  - Micromechanical properties of a hydroxyapatite/poly-L-lactide biocomposite using nanoindentation and modulus mapping
SP  - 1559
EP  - 1564
VL  - 27
IS  - 2-3
DO  - 10.1016/j.jeurceramsoc.2006.04.122
UR  - https://hdl.handle.net/21.15107/rcub_dais_14360
ER  - 

@article{
author = "Uskoković, Petar and Tang, Chak Yin and Tsui, C. P. and Ignjatović, Nenad and Uskoković, Dragan",
year = "2007",
abstract = "Biocomposites with ceramic fillers and polymer matrix are becoming attractive materials for bone tissue replacements. Nanoindentation has been used to locally characterize the surface mechanical properties of the hydroxyapatite/pOly-L-lactide (HAp/PLLA) biocomposite. Additionally, differences in the mechanical properties of HAP phase were successfully characterized as a function of surface morphology by using a highresolution modulus mapping technique. HAP granules consist of agglomerates of grainy clusters. Mechanical properties of ceramic grains and PLLA are in fair agreement with literature data. High-resolution methods were able to measure the properties of boundary phases between grains and the pore regions between particles in the agglomerate. After short-time immersion in distilled water, material surface showed a large decrease in storage modulus.",
publisher = "Oxford : Elsevier Sci Ltd.",
journal = "Journal of the European Ceramic Society",
title = "Micromechanical properties of a hydroxyapatite/poly-L-lactide biocomposite using nanoindentation and modulus mapping",
pages = "1559-1564",
volume = "27",
number = "2-3",
doi = "10.1016/j.jeurceramsoc.2006.04.122",
url = "https://hdl.handle.net/21.15107/rcub_dais_14360"
}

Uskoković, P., Tang, C. Y., Tsui, C. P., Ignjatović, N.,& Uskoković, D.. (2007). Micromechanical properties of a hydroxyapatite/poly-L-lactide biocomposite using nanoindentation and modulus mapping. in Journal of the European Ceramic Society
Oxford : Elsevier Sci Ltd.., 27(2-3), 1559-1564.
https://doi.org/10.1016/j.jeurceramsoc.2006.04.122
https://hdl.handle.net/21.15107/rcub_dais_14360

Uskoković P, Tang CY, Tsui CP, Ignjatović N, Uskoković D. Micromechanical properties of a hydroxyapatite/poly-L-lactide biocomposite using nanoindentation and modulus mapping. in Journal of the European Ceramic Society. 2007;27(2-3):1559-1564.
doi:10.1016/j.jeurceramsoc.2006.04.122
https://hdl.handle.net/21.15107/rcub_dais_14360 .

Uskoković, Petar, Tang, Chak Yin, Tsui, C. P., Ignjatović, Nenad, Uskoković, Dragan, "Micromechanical properties of a hydroxyapatite/poly-L-lactide biocomposite using nanoindentation and modulus mapping" in Journal of the European Ceramic Society, 27, no. 2-3 (2007):1559-1564,
https://doi.org/10.1016/j.jeurceramsoc.2006.04.122 .,
https://hdl.handle.net/21.15107/rcub_dais_14360 .

TY  - JOUR
AU  - Balać, Igor
AU  - Aleksendrić, Dragan
AU  - Tang, Chak Yin
AU  - Tsui, C.P.
AU  - Uskoković, Petar S.
AU  - Uskoković, Dragan
PY  - 2007
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/752
UR  - https://dais.sanu.ac.rs/123456789/13368
AB  - In this work, a combination of nanoindentation experiment and finite element modeling is proposed in order to obtain approximate material behavior of PLLA polymer in hydroxyapatite (HAp)/poly-L-lactide (PLLA) composite. Knowing these properties is important since the processing conditions used in hot pressing of composites with thermoplastic matrix strongly influence final mechanical properties of material in the solid state. A bi-linear material behavior is adopted for the polymer phase of the HAp/PLLA composite. Material behavior model, stress-strain curve, is determined by modulus of elasticity, yield stress and work-hardening rate. This combined method is proposed to determine material behavior before (modulus of elasticity) and after yield point (work hardening rate) of polymer phase after the hot-pressing of the composite. .
PB  - Savez inženjera metalurgije Srbije, Beograd
T2  - Metalurgija
T1  - Approximation of material behaviour of PLLA polymer in HAp/PLLA biocomposite material using nanoindentation and finite element method
SP  - 277
EP  - 286
VL  - 13
IS  - 4
UR  - https://hdl.handle.net/21.15107/rcub_dais_13368
ER  - 

@article{
author = "Balać, Igor and Aleksendrić, Dragan and Tang, Chak Yin and Tsui, C.P. and Uskoković, Petar S. and Uskoković, Dragan",
year = "2007",
abstract = "In this work, a combination of nanoindentation experiment and finite element modeling is proposed in order to obtain approximate material behavior of PLLA polymer in hydroxyapatite (HAp)/poly-L-lactide (PLLA) composite. Knowing these properties is important since the processing conditions used in hot pressing of composites with thermoplastic matrix strongly influence final mechanical properties of material in the solid state. A bi-linear material behavior is adopted for the polymer phase of the HAp/PLLA composite. Material behavior model, stress-strain curve, is determined by modulus of elasticity, yield stress and work-hardening rate. This combined method is proposed to determine material behavior before (modulus of elasticity) and after yield point (work hardening rate) of polymer phase after the hot-pressing of the composite. .",
publisher = "Savez inženjera metalurgije Srbije, Beograd",
journal = "Metalurgija",
title = "Approximation of material behaviour of PLLA polymer in HAp/PLLA biocomposite material using nanoindentation and finite element method",
pages = "277-286",
volume = "13",
number = "4",
url = "https://hdl.handle.net/21.15107/rcub_dais_13368"
}

Balać, I., Aleksendrić, D., Tang, C. Y., Tsui, C.P., Uskoković, P. S.,& Uskoković, D.. (2007). Approximation of material behaviour of PLLA polymer in HAp/PLLA biocomposite material using nanoindentation and finite element method. in Metalurgija
Savez inženjera metalurgije Srbije, Beograd., 13(4), 277-286.
https://hdl.handle.net/21.15107/rcub_dais_13368

Balać I, Aleksendrić D, Tang CY, Tsui C, Uskoković PS, Uskoković D. Approximation of material behaviour of PLLA polymer in HAp/PLLA biocomposite material using nanoindentation and finite element method. in Metalurgija. 2007;13(4):277-286.
https://hdl.handle.net/21.15107/rcub_dais_13368 .

Balać, Igor, Aleksendrić, Dragan, Tang, Chak Yin, Tsui, C.P., Uskoković, Petar S., Uskoković, Dragan, "Approximation of material behaviour of PLLA polymer in HAp/PLLA biocomposite material using nanoindentation and finite element method" in Metalurgija, 13, no. 4 (2007):277-286,
https://hdl.handle.net/21.15107/rcub_dais_13368 .

TY  - CONF
AU  - Balać, Igor
AU  - Tang, Chak Yin
AU  - Tsui, C. P.
AU  - Chen, D. Z.
AU  - Uskoković, Petar
AU  - Ignjatović, Nenad
AU  - Uskoković, Dragan
PY  - 2006
UR  - https://dais.sanu.ac.rs/123456789/11712
AB  - In order to obtain more accurate properties after compaction of hydroxyapatite (HAp)/poly-L-lactide (PLLA) composite, high-resolution measurement of mechanical properties method is proposed to determine the properties of each phase separately, leading to information that are valuable for the development of new materials as well as for predictive modeling purposes. The PLLA polymer processing conditions used in hot pressing of the composite strongly influence final mechanical properties of the material in the solid state. Since the aim was to measure PLLA material properties, acceptable findings could only be made using unconstrained, cured in situ nanoindentation tests. A finite element analysis of the in situ indentation experiment was performed to determine required size of plain polymer area, needed for indentation test, which would minimize the particle influence on the matrix elastic behavior.
PB  - Durnten-Zurich : Trans Tech Publications Ltd.
C3  - Recent Developments in Advanced Materials and Processes
T1  - Nanoindentation of in situ polymers in hydroxyapatite/poly-L-lactide biocomposites
SP  - 501
EP  - 506
DO  - 10.4028/www.scientific.net/MSF.518.501
UR  - https://hdl.handle.net/21.15107/rcub_dais_11712
ER  - 

@conference{
author = "Balać, Igor and Tang, Chak Yin and Tsui, C. P. and Chen, D. Z. and Uskoković, Petar and Ignjatović, Nenad and Uskoković, Dragan",
year = "2006",
abstract = "In order to obtain more accurate properties after compaction of hydroxyapatite (HAp)/poly-L-lactide (PLLA) composite, high-resolution measurement of mechanical properties method is proposed to determine the properties of each phase separately, leading to information that are valuable for the development of new materials as well as for predictive modeling purposes. The PLLA polymer processing conditions used in hot pressing of the composite strongly influence final mechanical properties of the material in the solid state. Since the aim was to measure PLLA material properties, acceptable findings could only be made using unconstrained, cured in situ nanoindentation tests. A finite element analysis of the in situ indentation experiment was performed to determine required size of plain polymer area, needed for indentation test, which would minimize the particle influence on the matrix elastic behavior.",
publisher = "Durnten-Zurich : Trans Tech Publications Ltd.",
journal = "Recent Developments in Advanced Materials and Processes",
title = "Nanoindentation of in situ polymers in hydroxyapatite/poly-L-lactide biocomposites",
pages = "501-506",
doi = "10.4028/www.scientific.net/MSF.518.501",
url = "https://hdl.handle.net/21.15107/rcub_dais_11712"
}

Balać, I., Tang, C. Y., Tsui, C. P., Chen, D. Z., Uskoković, P., Ignjatović, N.,& Uskoković, D.. (2006). Nanoindentation of in situ polymers in hydroxyapatite/poly-L-lactide biocomposites. in Recent Developments in Advanced Materials and Processes
Durnten-Zurich : Trans Tech Publications Ltd.., 501-506.
https://doi.org/10.4028/www.scientific.net/MSF.518.501
https://hdl.handle.net/21.15107/rcub_dais_11712

Balać I, Tang CY, Tsui CP, Chen DZ, Uskoković P, Ignjatović N, Uskoković D. Nanoindentation of in situ polymers in hydroxyapatite/poly-L-lactide biocomposites. in Recent Developments in Advanced Materials and Processes. 2006;:501-506.
doi:10.4028/www.scientific.net/MSF.518.501
https://hdl.handle.net/21.15107/rcub_dais_11712 .

Balać, Igor, Tang, Chak Yin, Tsui, C. P., Chen, D. Z., Uskoković, Petar, Ignjatović, Nenad, Uskoković, Dragan, "Nanoindentation of in situ polymers in hydroxyapatite/poly-L-lactide biocomposites" in Recent Developments in Advanced Materials and Processes (2006):501-506,
https://doi.org/10.4028/www.scientific.net/MSF.518.501 .,
https://hdl.handle.net/21.15107/rcub_dais_11712 .

TY  - CONF
AU  - Tang, Chak Yin
AU  - Ignjatović, Nenad
AU  - Uskoković, Dragan
AU  - Uskoković, Petar S.
AU  - Chan, K.C.
AU  - Lo, S.C.L.
AU  - Lee, Tai Chiu
PY  - 2004
UR  - https://dais.sanu.ac.rs/123456789/14300
AB  - This study descripts processing of biphasic calcium-phosphate (BCP) and poly-L-lactide (PLLA) biocomposite implant material. The composite was obtained by mixing completely dissolved PLLA with granules of high crystalline BCP and was compacted by hot pressing using cylindrical dies at 450 K temperature and 98.1 MPa pressure, for 30 and 60 minutes. Wide-angle Xray structural (WAXS) analyses of BCP, PLLA and BCP/PLLA composite blocks were made followed by calorimetric (DSC) tests in the 320-520 K temperature range. Compression tests revealed that Young’s modulus and compressive strength of the composite increased with extended hot pressing time and were found to be within the bounds of the cortical bone values.
PB  - Trans Tech Publications, Ltd.
C3  - Advances in Materials Manufacturing Science and Technology
T1  - Processing and Mechanical Properties of Biphasic Calcium-Phosphate/Poly-L-Lactide Composite Biomaterials
SP  - 273
EP  - 277
DO  - 10.4028/www.scientific.net/MSF.471-472.273
UR  - https://hdl.handle.net/21.15107/rcub_dais_14300
ER  - 

@conference{
author = "Tang, Chak Yin and Ignjatović, Nenad and Uskoković, Dragan and Uskoković, Petar S. and Chan, K.C. and Lo, S.C.L. and Lee, Tai Chiu",
year = "2004",
abstract = "This study descripts processing of biphasic calcium-phosphate (BCP) and poly-L-lactide (PLLA) biocomposite implant material. The composite was obtained by mixing completely dissolved PLLA with granules of high crystalline BCP and was compacted by hot pressing using cylindrical dies at 450 K temperature and 98.1 MPa pressure, for 30 and 60 minutes. Wide-angle Xray structural (WAXS) analyses of BCP, PLLA and BCP/PLLA composite blocks were made followed by calorimetric (DSC) tests in the 320-520 K temperature range. Compression tests revealed that Young’s modulus and compressive strength of the composite increased with extended hot pressing time and were found to be within the bounds of the cortical bone values.",
publisher = "Trans Tech Publications, Ltd.",
journal = "Advances in Materials Manufacturing Science and Technology",
title = "Processing and Mechanical Properties of Biphasic Calcium-Phosphate/Poly-L-Lactide Composite Biomaterials",
pages = "273-277",
doi = "10.4028/www.scientific.net/MSF.471-472.273",
url = "https://hdl.handle.net/21.15107/rcub_dais_14300"
}

Tang, C. Y., Ignjatović, N., Uskoković, D., Uskoković, P. S., Chan, K.C., Lo, S.C.L.,& Lee, T. C.. (2004). Processing and Mechanical Properties of Biphasic Calcium-Phosphate/Poly-L-Lactide Composite Biomaterials. in Advances in Materials Manufacturing Science and Technology
Trans Tech Publications, Ltd.., 273-277.
https://doi.org/10.4028/www.scientific.net/MSF.471-472.273
https://hdl.handle.net/21.15107/rcub_dais_14300

Tang CY, Ignjatović N, Uskoković D, Uskoković PS, Chan K, Lo S, Lee TC. Processing and Mechanical Properties of Biphasic Calcium-Phosphate/Poly-L-Lactide Composite Biomaterials. in Advances in Materials Manufacturing Science and Technology. 2004;:273-277.
doi:10.4028/www.scientific.net/MSF.471-472.273
https://hdl.handle.net/21.15107/rcub_dais_14300 .

Tang, Chak Yin, Ignjatović, Nenad, Uskoković, Dragan, Uskoković, Petar S., Chan, K.C., Lo, S.C.L., Lee, Tai Chiu, "Processing and Mechanical Properties of Biphasic Calcium-Phosphate/Poly-L-Lactide Composite Biomaterials" in Advances in Materials Manufacturing Science and Technology (2004):273-277,
https://doi.org/10.4028/www.scientific.net/MSF.471-472.273 .,
https://hdl.handle.net/21.15107/rcub_dais_14300 .

TY  - JOUR
AU  - Balać, Igor
AU  - Milovančević, Milorad
AU  - Tang, Chak Yin
AU  - Uskoković, Petar S.
AU  - Uskoković, Dragan
PY  - 2004
UR  - https://dais.sanu.ac.rs/123456789/13319
AB  - A three-dimensional (3D) finite element (FE) unit cell model is applied to studies on the elastic properties of ceramic spherical particle-polymer composite. In this model, hydroxyapatite particles (HAp) are assumed to be spherical and are arranged on a face-centered cubic (FCC) array in poly-L-lactide (PLLA) matrix surrounding. The three dimensionality of the proposed model enables simulation of elastic properties as well as developed stress states. The FE calculations provide estimates of compressive elastic modulus, shear modulus, Poisson's ratio and stress state of the composite for a range of particle volume fractions. The FCC unit cell FE models are evaluated by comparison to available experimental results, simple cubic (SC) unit cell FE calculations and Halpin-Tsai equations. In applying unit cell models for predicting elastic properties of particle-filled composites, the FCC arrangement can be observed to be more accurate compared with the SC arrangement.
PB  - Elsevier, Amsterdam
T2  - Materials Letters
T1  - Estimation of elastic properties of a particulate polymer composite using a face-centered cubic FE model
SP  - 2437
EP  - 2441
VL  - 58
IS  - 19
DO  - 10.1016/j.matlet.2004.02.033
UR  - https://hdl.handle.net/21.15107/rcub_dais_13319
ER  - 

@article{
author = "Balać, Igor and Milovančević, Milorad and Tang, Chak Yin and Uskoković, Petar S. and Uskoković, Dragan",
year = "2004",
abstract = "A three-dimensional (3D) finite element (FE) unit cell model is applied to studies on the elastic properties of ceramic spherical particle-polymer composite. In this model, hydroxyapatite particles (HAp) are assumed to be spherical and are arranged on a face-centered cubic (FCC) array in poly-L-lactide (PLLA) matrix surrounding. The three dimensionality of the proposed model enables simulation of elastic properties as well as developed stress states. The FE calculations provide estimates of compressive elastic modulus, shear modulus, Poisson's ratio and stress state of the composite for a range of particle volume fractions. The FCC unit cell FE models are evaluated by comparison to available experimental results, simple cubic (SC) unit cell FE calculations and Halpin-Tsai equations. In applying unit cell models for predicting elastic properties of particle-filled composites, the FCC arrangement can be observed to be more accurate compared with the SC arrangement.",
publisher = "Elsevier, Amsterdam",
journal = "Materials Letters",
title = "Estimation of elastic properties of a particulate polymer composite using a face-centered cubic FE model",
pages = "2437-2441",
volume = "58",
number = "19",
doi = "10.1016/j.matlet.2004.02.033",
url = "https://hdl.handle.net/21.15107/rcub_dais_13319"
}

Balać, I., Milovančević, M., Tang, C. Y., Uskoković, P. S.,& Uskoković, D.. (2004). Estimation of elastic properties of a particulate polymer composite using a face-centered cubic FE model. in Materials Letters
Elsevier, Amsterdam., 58(19), 2437-2441.
https://doi.org/10.1016/j.matlet.2004.02.033
https://hdl.handle.net/21.15107/rcub_dais_13319

Balać I, Milovančević M, Tang CY, Uskoković PS, Uskoković D. Estimation of elastic properties of a particulate polymer composite using a face-centered cubic FE model. in Materials Letters. 2004;58(19):2437-2441.
doi:10.1016/j.matlet.2004.02.033
https://hdl.handle.net/21.15107/rcub_dais_13319 .

Balać, Igor, Milovančević, Milorad, Tang, Chak Yin, Uskoković, Petar S., Uskoković, Dragan, "Estimation of elastic properties of a particulate polymer composite using a face-centered cubic FE model" in Materials Letters, 58, no. 19 (2004):2437-2441,
https://doi.org/10.1016/j.matlet.2004.02.033 .,
https://hdl.handle.net/21.15107/rcub_dais_13319 .