Effect of air plasma treatment on mechanical properties of bioactive composites for medical application: Composite preparation and characterization

Mehboob, Hassan,Bae, Ji-Hun,Han, Min-Gu,Chang, Seung-Hwan Elsevier 2016 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.143 No.-

<P><B>Abstract</B></P> <P>The aim of this study was to fabricate unidirectional bio-glass fibers (BGF) (13-93)-reinforced polylactic acid (PLA) composites with improved mechanical properties for a bone plate to heal the weight-bearing long-bone fractures. Various exposure times of air plasma (30, 60, 90 and 120s) on BGF fibers were studied, and the most suitable conditions were determined for the fabrication of the BGF/PLA composite. Mechanical properties, microscopic characteristics, <I>in vitro</I> degradation and the bioactivity of the BGF/PLA composites were evaluated. Fatigue life of 30s plasma treated composites completed 1 million cycles when actual loading conditions (10–20% body weight) were used. 30s plasma treated specimens showed increase in tensile strength, flexural strength and interlaminar shear strength as 31%, 13.5% and 33%, respectively. The SEM image of fractured surface of 30s plasma treated composite suggested that the failure was shifted to the PLA which is evidence of superior bonding between fiber and PLA matrix. Moreover, a bone-like calcium-phosphate layer was precipitated on the surface of degraded composite that is essential for bone healing.</P>

A study of the tissue differentiation process when biodegradable composite bone plate was used

Hassan Mehboob,S. H. Chang(장승환) 한국정밀공학회 2014 한국정밀공학회 학술발표대회 논문집 Vol.2014 No.5월

Finite element modelling and characterization of 3D cellular microstructures for the design of a cementless biomimetic porous hip stem

Mehboob, Hassan,Tarlochan, Faris,Mehboob, Ali,Chang, Seung-Hwan Elsevier 2018 Materials & Design Vol.149 No.-

<P><B>Abstract</B></P> <P>Titanium porous cellular microstructures are commonly used in bone mimetic implants. The orientations of the internal strut architectures of these microstructures affect the mechanical performance under various loads; however, poor architectural designs may result in their failure. Three-dimensional (3D) finite element models of cubic, diamond, and body-centered cubic (BCC) geometries were constructed with 1<B>–</B>4 numbers of unit cells and 4–10-mm unit cell size. Mechanical testing of the finite models of the cubic, diamond, and BCC structures with porosities of 20–90% was performed under compression, bending, and torsional loads. The BCC structure showed moderate and relatively isotropic mechanical properties compared with those of the diamond and cubic structures. A design space for a BCC porous structure with a porosity of 40–65% was estimated to model a complete porous stem to mimic the bone properties. Furthermore, the stems with the determined porous mechanical properties of the BCC microstructures with 20–90% porosities were tested under physiological loading conditions. It was found that a porosity of 47.3% of the BCC structure exhibits the closest stiffness (469N/mm) to an intact bone (422N/mm). This was predicted by our suggested design space of the porosity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bioinspired 3D FE models of porous cellular structures with cubic, diamond, and body centered cubic geometries were constructed. </LI> <LI> Mathematical simplified relationship for porosity calculation was derived with less than 6% error between theoretical and CAD models. </LI> <LI> 20–90% porous cellular structures were tested under compression, bending and torsional loads. </LI> <LI> Gibson and Ashby and regression models were utilized to correlate the mechanical properties from FEA results. </LI> <LI> A design space of BCC porous structure with porosity of 40–65% was determined and 47.3% porous stem gave the similar stiffness to the bone. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Evaluation of the healing performance of fractured tibia when functionally graded composite bone plate was applied

Hassan Mehboob,Seung-Hwan Chang 한국정밀공학회 2013 한국정밀공학회 학술발표대회 논문집 Vol.2013 No.10월

Sustainable Utilization of Powdered Glass to Improve the Mechanical Behavior of Fat Clay

Hassan Mujtaba,Usama Khalid,Khalid Farooq,Mehboob Elahi,Ziaur Rehman,Hussain Mustafa Shahzad 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.12

Civil engineering infrastructure like roads, bridges, railway tracks, and building structures constructed on fat clay becomes suspicious due to adverse change in the behavior of such soil on interaction with water. To solve such problems especially in underdeveloped countries, application of industrial waste like glass is associated with technical, financial, and environmentalbenefits. Emphasis of current study is to determine the consequences of powdered glass (GC) on mechanical behavior of fat clay. A fat clayey sample was collected from location of Nandipur, and glass was taken from local glass market in powdered form. Samples were remolded at optimum moisture content and maximum dry unit weight by mixing GC up to 14%. Soil classification tests, modified compaction tests, unconfined compression tests, one-dimensional consolidation tests, California bearing ratio (CBR) tests, and scanning electron microscope were performed. With increasing GC, the consistency limits, compression characteristics, swell characteristics, and optimum moisture content decreased while maximum dry unit weight, yield stress, CBR, and unconfined compression strength increased. Influence of GC is also observed on microstructure of treated clay. After 12% GC, aforementioned geotechnical characteristics behave inversely for selected clay. The optimum GC-value for the tested clay is about 12%, however, this value may vary from clay to clay.

Influence of functionally graded pores on bone ingrowth in cementless hip prosthesis: a finite element study using mechano-regulatory algorithm

Tarlochan, Faris,Mehboob, Hassan,Mehboob, Ali,Chang, Seung-Hwan Springer-Verlag 2018 Biomechanics and modeling in mechanobiology Vol.17 No.3

Biomechanical design of a composite femoral prosthesis to investigate the effects of stiffness, coating length, and interference press fit

Tarlochan, Faris,Mehboob, Hassan,Mehboob, Ali,Chang, Seung-Hwan Elsevier 2018 Composite structures Vol.204 No.-

<P><B>Abstract</B></P> <P>Traditionally, high stiffness hip prostheses are associated with aseptic loosening. Hence, the effects of stiffness, coating length, and interference press fit on load sharing and micro-movements are investigated for a better understanding from a mechanical perspective. A simplified 3D model of the femur and prostheses composed of cobalt chrome (CoCr), titanium (Ti), and glass/polypropylene (Twintex [0]<SUB>2nT</SUB>) composite are constructed. Three interference fits corresponding to 5, 25, and 50 µm are used with half, three-quarter, and full lengths of coating that are used to assemble the prostheses with bones to investigate micro-movements at the bone-prosthesis interfaces, interfacial failure, and stress transfer to the bone. The reaction forces of body weight and muscular forces in the femur are used to simulate the FE model. The results indicate that the CoCr and Ti prostheses exhibit low micro-movements at the proximal end and high micro-movements at the distal end and vice versa for the Twintex [0]<SUB>2nT</SUB> composite prosthesis. Uniformity of stress transfer to the bone along the prosthesis efficiently increases with increases in the coating lengths and interference press fits for all the cases. A fully coated length of Twintex [0]<SUB>2nT</SUB> composite prosthesis with a 50-µm interference press fit provides the most efficient load sharing and stress transfer to the bone and micro-movements at the bone–prosthesis interface.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

특집 논문(特輯 論文) : 메카노 규제 이론에 기초한 복합재료 IM-rod가 적용된 골절부의 세포분화과정의 유한요소해석

손대성 ( Dae Sung Son ),( Hassan Mehboob ),장승환 ( Seung Hwan Chang ) 한국복합재료학회 2012 Composites research Vol.25 No.5

본 논문에서는 복합재료 IM rod가 적용된 골절부의 세포 분화과정을 모사하기 위해 유한요소해석을 실시하였다. 세포의 골화과정을 해석하기 위해 편향 변형률을 이용한 메카노 규제 이론을 사용하였으며, 반복 계산을 위해 Python 코드를 이용하여 서브루틴을 구현하였다. 치료에 가장 적절한 복합재료 IM rod의 강성을 찾기 위해 직물 탄소섬유/에폭시 복합재료 (WSN3k)의 적층각도를 바꾸어 해석을 실시하였다. 골절부에 가해지는 기계적 자극에 따른 치료효율을 비교하기 위해 두 가지 초기 하중 조건을 적용하였다. 그 결과 치료효율은 강성의 차이보다 하중에 의해 큰 영향을 받았으며, 초기 하중이 몸무게의 10%이고, 적층순서가 [±45]nT일 때 치료효율이 가장 높았다. This paper describes the bone healing process of fractured long bones such as a tibia applied by composite IM rods using finite element analysis. To simulated tissue differentiation process mechano-regulation theory with a deviatoric strain was implemented and a user`s subroutine programmed by a Python code for an iterative calculation was used. To broadly find the appropriate rod modulus for healing bone fractures, composite IM rods were analyzed considering the stacking sequence. To compare mechanical stimulation at fracture gap, two kinds of initial loading conditions were applied. As a result, it was found that the initial loading condition was the most sensitive factor for the healing performance. In case a composite IM rod made of a plain weave carbon fiber/epoxy (WSN3k) had a stacking sequence of [±45]nT, the healing efficiency was the most effective under a initial load of 10%BW.

A Residual Stress Evaluation in Laser Welded Lap Joint with Hole Drilling Method

박명균,이수진,Behzad Ahmed Zai,Hassan Mehboob,Rashid Ali Sindhu 한국정밀공학회 2009 International Journal of Precision Engineering and Vol.10 No.5

Residual stresses deteriorate strength of materials affecting the quality of industrial products. A removal or reduction of the residual stresses is an essential procedure in successful engineering component development. Effective and convenient methods are necessary for detection and evaluation of residual stresses. In this paper Hole Drilling Method is chosen for identification and a quantitative determination of the residual stresses in specimens of two groups under different laser welding speed conditions, 4.1m/min and 5.1m/min. The lap joints welded with STS 301L sheet of two different speeds were investigated along the welding line at two locations, the middle and the end location in the heat affected zone (HAZ). The identification of HAZ is carried out by taking hardness values from weld centerline to the raw material. Based on the experimental results and analysis, it is found that higher welding speed reduces the residual stresses. Also, the end location is found to be higher residual stress area compared with middle location due to the convective boundary condition. The residual stresses decrease as the depth increases from the top surface due to the lower heat input to depth increments.

Effect of moisture absorption on damping and dynamic stiffness of carbon fiber/epoxy composites

Behzad Ahmed Zai,박명균,H. S. Choi,Hassan Mehboob,Rashid Ali 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.11

In this paper, the damping and dynamic stiffness of UHN125C carbon fiber/epoxy composite beam was experimentally measured. The effect of fiber orientation angle and stacking sequences on damping, resonance frequency, and dynamic stiffness was discussed with a focus on the effect of moisture absorption. Dried specimens were immersed in distilled water for a certain period to absorb water for 8, 16, and 24 d, respectively, and the moisture content absorbed in the specimen was measured. Furthermore, using the impact hammer technique, the measurements of dynamic responses were conducted on a cantilever beam specimen with one end clamped by bolts and metal plates. The damping properties in terms of loss factor were approximated by half-power bandwidth technique. The dynamic stiffness was evaluated using resonance frequency as a function of moisture content. The damping increased with the increase of moisture content; however, the dynamic stiffness reduced with the reduction of resonance frequency. The results of the dynamic stiffness were aided by measuring the dynamic strain using DBU-120A strain-indicating software. The increment in the dynamic strain strengthened the results obtained for dynamic stiffness.