Liviu Marsavina

Liviu Marsavina
Polytechnic University of Timişoara · Department of Mechanics and Strength of Materials

Professor

About

348
Publications
113,417
Reads
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5,281
Citations
Additional affiliations
January 2007 - July 2008
Lublin University of Technology
Position
  • Marie Curie - More Experienced Researcher
July 2001 - July 2002
The University of Sheffield
Position
  • Research Associate
February 2000 - August 2000
Loughborough University
Position
  • PostDoc Position

Publications

Publications (348)
Article
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Background and Clinical Significance: Since their first introduction in the early 1950s, hip prostheses implants are becoming increasingly reliable; nevertheless, failures can still happen. The focus of this paper is to present a case study on a catastrophic fractured hip prosthesis liner that consequently led to revision surgery and the replacemen...
Article
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Background Cancellous bone mechanical properties are directly linked to structural integrity, which is a result of bone quantity, the quality of its bone matrix, and its microarchitecture. Several studies highlighted the bone behavior under specific loads, contributing to understanding risk factors and developing more effective therapeutic strategi...
Article
Cellular materials in general and foams (polymeric, metallic and ceramic) in particular have seen a major development in recent years. Most of the data are reported at room temperature (RT), while the area of extreme temperatures is little studied. This work presents the quasi-static compression behavior of metallic foams (MFs). The MFs have closed...
Article
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Additive manufacturing (AM) is revolutionizing various industries by enabling the creation of complex structures with minimal waste. In the context of a circular economy, the importance of recycling cannot be overstated, as it plays a crucial role in reducing environmental impact and conserving resources. This study investigates the mechanical beha...
Article
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The oral cavity's soft and hard tissues create a conducive environment for microbial proliferation and biofilm development, facilitating the colonization of prosthodontic and implant materials such as titanium (Ti) and zirconia (Zr). This study aimed to compare the efficacy of conventional decontamination methodologies (i.e., chemical and mechanica...
Conference Paper
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Polylactic Acid (PLA) is a widely used material in Fused Deposition Modeling (FDM) technology. Additive Manufacturing (AM) parameters are known to have an influence on the mechanical properties of final components. In FDM, the layer thickness is an influencing parameter providing overall better mechanical properties with lower layer thickness value...
Conference Paper
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Additive manufacturing provides significant advantages over conventional manufacturing. Among the others, the almost unconstrained freedom in the geometrical design for this technology can be pointed out. However, the geometrical complexness of such components requires for adequate tools to assess both their fracture behavior and fatigue life. A su...
Article
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Currently, to reduce CO2 emissions and fuel consumption, the automotive industry seeks to replace high-density components with low-density ones. Due to their advantageous properties (high stiffness/strength-to-weight ratio and high energy absorption performances), metallic foams (MFs) are identified as ideal candidates for this purpose. This paper...
Article
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Currently, the automotive industry is looking for their new products to have a density as low as possible so that CO 2 emissions decrease. Metallic foams have attracted a great deal of interest in this industry because of their multiple advantages. They can be produced at a relatively low cost and have advantageous properties, especially due to the...
Article
Polycarbonate based thermoplastics are frequently used in several engineering applications as a consequence of their relatively low price to mechanical toughness ratio, making these materials a perfect choice for various products which, during their lifetime, are subjected to different kinds of external loads. This study is meant to investigate the...
Conference Paper
The paper presents an experimental investigation of the impact properties and imperfections of the 3D printed Al4043A aluminium-silicium alloy using wire-arc additive manufacturing. Using an experimental program based on factorial experiments, correlations between the main WAAM process parameters and the related properties of the deposition were de...
Article
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Fabrication based on additive manufacturing (AM) process from a three-dimensional (3D) model has received significant attention in the last few years. The present paper presents the mechanical characterization of 3D printed specimens based on fused deposition modelling (FDM), which is one of the most commonly used AM methods. Tensile and fatigue te...
Article
In the present paper, the fracture toughness of a polyurethane (PUR) foam (manufactured by Necumer GmbH, Germany, under the commercial designation Necuron 651) is experimentally and numerically investigated in order to examine its dependence on the specimen sizes. As a matter fact, to the best knowledge of the present authors, such an analysis is s...
Article
The Theory of Critical Distances (TCD) has undoubtedly represented a breakthrough in the brittle failure assessment of engineering materials containing defects, crack, or notches. The basic idea on which the simplest formulation of the TCD is based is to evaluate an effective stress at a characteristic distance from the tip of the defect/crack/notc...
Article
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This work investigates the dynamic response of a Rugby union protective headgear under frontal impact. The model used in the numerical analyses was developed based on commercially available products, and consisted of a shell padded with prismatic elements. The material model used for the padding consisted of a hyperfoam formulation and was calibrat...
Article
The Theory of Critical Distances (TCD) has undoubtedly represented a breakthrough in the brittle failure assessment of engineering materials containing defects, crack or notches. The basic idea on which the simplest formulation of the TCD is based is to evaluate an effective stress at a characteristic distance from the tip of the defect/crack/notch...
Article
Additive manufacturing (AM) is a process that can achieve many parts with complex features in the production. The most important aspect of AM is that there is no material wastage, which reduces costs. The benefits of AM have been noticed and the process is now being used in many fields like in medicine, in automotive, in aircraft, etc. Additive man...
Article
The paper deals with the effect of the sample shape on the uniaxial compression behavior of powder metallurgically prepared closed cell aluminum foams with surface skin. The combination of various geometry shapes of aluminum foams is important in the case of design and development of optimal seismic and impact energy absorbers. Aluminum foam sample...
Article
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The tarpaulin of PVC-coated S8210 wagons is a composite textile membrane. This material is resistant to atmospheric factors (wind, rain, snow, etc.), durable for many practical applications and can be manufactured in various colors and prints. PVC membrane material is inexpensive, soft and easy to manufacture. These materials are widely used in lar...
Article
The paper presents the dynamic impact properties of laser-sintered polyamide PA2200 in accordance with the building orientation. The idea of determining the impact properties in relation to building orientation lays on orientation-property dependence founded in our previous studies of tensile, bending and fracture mechanics testing. The specimens w...
Article
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Determining the mechanical properties of additive manufacturing (AM) components manifest high interest of many researchers nowadays. Fused deposition modelling (FDM) is a widely spread 3D printing, due to its many advantages: low cost, good speed, minimum wastage, and simplicity of material conversion. This paper presents a study of the tensile mec...
Article
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Fused Deposition Modeling (FDM), also known as material extrusion, is currently one of the most popular Additive Manufacturing (AM) technology on the market. In this study, two commercial FDM printers (Prusa i3 MK3 and WN400 3D Platform) were used for layer-by-layer manufacturing of polylactic acid (PLA) Dog Bone (DB) and Single Edge Notched Bend (...
Article
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Additive manufacturing (AM) is a topical field today and has received the attention of many researchers. However, further research is needed to overcome the many challenges facing AM, especially in the mixed-mode fracture. The results presented in this paper are framing the experimental data obtained for mixed-mode I/II fracture properties of laser...
Article
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Bone scaffolds must fulfil numerous and sometimes contradictory characteristics: biocompatibility, bioactivity, high porosity, and appropriate mechanical strength. To tackle some of these is-sues, this study has several aims for the development of such scaffolds for dentistry applications: (i) to utilize appropriate materials (ceramics and sponges)...
Article
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Finite Fracture Mechanics and Cohesive Crack Model can effectively predict the strength of plain, cracked or notched structural components, overcoming the classical drawbacks of Linear Elastic Fracture Mechanics. Aim of the present work is to investigate size effects by expressing each model as a unified system of two equations, describing a stress...
Conference Paper
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The majority of manufacturers of polymer filaments for FDM technology rely their datasheets only on tensile tests, so their documentation usually lacks any data concerning fracture mechanics parameters. Having in mind the importance of fracture mechanics parameters in material design and application e.g., plane-strain fracture toughness, and the fa...
Article
Attempts to reduce energy consumption and concerns about global environmental protection have led to increased interest in the use of lightweight materials, especially in areas such as the automotive and aerospace industries. This paper analyzes experimentally the effect of size on the fatigue duration of Mg alloys, considering the defects resultin...
Article
The presented article discusses the fracture behavior of two short fiber reinforced polymers (SFRP): a polyphthalamide (PPA) with glass fiber inclusions of 33% (GF33) and a polyphenylene sulfide (PPS) with glass fiber inclusions of 40% (GF40). The behavior of these two materials was characterized as brittle and highly orthotropic in accordance with...
Article
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The paper proposed an alternative optical metrology to classical methods (strain gauge measurements and numerical simulation) for strain determination on printed circuit board (PCBs) due to thermal loads. The digital image correlation (DIC) technique was employed to record the strain distribution in some particular areas of the PCB. A thermal load...
Article
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In the automotive industry and not only, more and more attempts are being made to replace parts made of metals with those made of plastics, due to their low weight and low manufacturing cost. Thus, a detailed knowledge of the mechanical properties of polymeric materials is a must. This paper presents a study of the influence of temperature on the t...
Article
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Keywords • ABS (acrylonitrile butadiene styrene) • vibration • deposition direction • frequency response function • additive manufacturing Abstract This article compares the vibrational behaviour variability of acrylonitrile butadiene styrene (ABS) test specimens obtained by additive manufacturing (AM) with three different deposition directions. Te...
Article
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Photopolymerization, based on light-induced radical polymerization, is nowadays exploited in additive manufacturing (AM) technologies enabling to achieve high dimensional quality. The mechanical properties of the obtained material are heavily dependent on the chemistry of the photopolymer and on the way the AM process is performed. Here we study, t...
Article
Metal sheet anisotropy is the directional dependence of mechanical properties. It is the key factor that must be considered when using numerical simulation to predict any manufacturing process that involves plastic deformation. The plastic strain ratio, also known as Lankford coefficients or R values, together with the forming limit curves (FLC), a...
Article
Purpose/Aim The focus of this study is twofold; the first objective is to evaluate the resistance of veneer-retained anterior fixed partial dentures to compression testing. The second objective is to determine if veneer retainers with these axial grip extensions improve the restorations resistance to compressive forces as demand for biomaterial and...
Article
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The paper presents experimental results of the crack path in Semi-Circular Bend (SCB) specimens obtained through additive manufacturing using Selective Laser Sintering (SLS) process. Determination of fracture parameters for components obtained via Additive manufacturing is a challenging topic, due to the influence of manufacturing parameters on the...
Article
Full-text available
Additive manufacturing (AM) is a process that can achieve many parts with complex features in the production. The most important aspect of AM is that there is no more material wastage, which reduces costs. Additive manufacturing is beginning to be used in many fields, in medicine, in automotive, in aircraft, etc. The method of layer-by-layer additi...
Article
Full-text available
The Semi Circular Bend Specimens loaded in symmetric three point bending were considered to investigate the size effect in PLA and PETG specimens obtained using FDM technology. Four specimen sizes were manufactured with radius R = 10, 20, 30 and 40 mm, with thickness of 6 mm and tested. A strong size effect for PLA and PETG materials obtained throu...
Article
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Sheet metal anisotropy is the directional dependence of mechanical properties. It is a critical factor that must be considered when using numerical simulation to predict any plastic deformation manufacturing process. Sheet metals prove anisotropic plastic behaves due to crystallographic texture caused by progressive rolling steps, Banabic D. et al....
Article
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Photopolymerization is an advanced technology to trigger free radical polymerization in a liquid monomer solution through light-induced curing, during which mechanical properties of the material are significantly transformed. Widely used in additive manufacturing, parts fabricated with this technique display precisions up to the nanoscale; however,...
Article
Rigid foam materials are among the low strength structural components that can be failed catastrophically under mechanical loads. Low fracture toughness is therefore a major failure mode in these materials and researchers try to find suitable testing methods for determining the fracture toughness of foam materials. In this research a suitable test...
Article
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This paper investigates the effects of layers orientation on impact energy absorbed by acrylonitrile butadiene styrene (ABS) test specimens, obtained by additive manufacturing (AM), having three in‐plane deposition directions (0°, 45°, and 90°). The specimens were tested with instrumented Charpy hammer, CEAST 9050 Pendulum Impact System, according...
Article
This paper presents an experimental testing of two short-fiber reinforced composites (SFRC). The two materials are a polyphthalamide with 33% glass fiber inclusion (PPA-GF33) and a polyphenylene sulfide with 40% glass fiber inclusion. Rectangular plates were obtained from these two materials by injection molding. Specimens, type 1BA, according to I...
Article
The present article discusses the fracture behavior of medium-density fiberboard (MDF) and particleboard (PB), under mixed mode loading conditions. With wide applications in construction, marine and furniture industry, MDF and PB are two well-known, wood-based composites that are made of wood particles and fibers, adhered together using a standard...
Article
Polycarbonate composites are widely spread in many industries, for product manufacturing. Although these materials are being used with high fidelity, their mechanical properties will highly depend on: manufacturing processes, fiber orientations with respect to external loads, type of loading, environmental conditions etc. This paper presents the Ch...
Article
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The CAD/CAM techniques, especially additive manufacturing such as 3D printing, constitute an ever-growing part of obtaining different dental appliances and restorations. Of these, provisional restorations are of frequent use in daily dental practice and are the object of this study. Masticatory and parafunctional forces determine flexure on these p...
Article
Based on their special stochastically distributed pores, Composite Metallic Foams (CMFs) represent a promising alternative to the conventional high-density solid structures. However, due to their high sensitivity to temperature changes, the effect of testing temperature on the compression behaviour of CMFs should not be neglected. In this paper, th...
Article
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This paper presents manufacturing, testing and computing steps for determining the fracture toughness property of polyamide PA 2200 processed by laser sintering using different process parameters. The design of the samples was conducted according to ASTM D 5045‐99 and ASTM D 5528 – 01, and the fracture tests consist of four‐point bending in symmetr...
Article
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This work investigates the possibility to apply the strain energy density method, as regards blunt V-notches under mixed loading condition, through finite element models with a free mesh pattern. It is worth underlining that the conventional procedure for the application of this method to this kind of components requires two different numerical sim...
Article
One accepted cause that generates low mechanical strength and/or fracture properties is the presence of defects in the structure of the material. Additive Manufacturing does not except this rule, especially the powder bed fusion technologies that relays on powder spreading through a mechanical blade or roller followed by laser sintering or melting....
Article
In this paper, the mechanical behavior of hyperelastic foams used in athletic footwear soles is investigated for compression and tensile loadings. Specimens were cut using profiled tools from aged footwear manufactured by five different companies. Based on the experimental results, the modified Ogden hyperelastic strain-energy density function was...
Article
Within this paper, a numerical study was performed, aiming to assess the influence of fiber orientation on the mechanical properties of tensile specimens, by using the finite element method. The specimen, designed according to ISO-527-2, is type 1BA and consists of a reinforced polyamide with 30% glass fiber (PA66 GF30). The specimens were extracte...
Article
The objective of this paper is to detail the steps taken in creating a material model capable of describing the micromechanical behavior of a composite material made up of a polyphthalamide matrix reinforced with glass fiber inclusions. The composite material model was created using the specialized software program Digimat, through its Mean-Field a...
Article
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This work investigates the mechanical behaviour of woven carbon composites using a multi-scale approach. With the commercial software Digimat, the woven structure was developed based on microscopic observations (yarn pattern and density). Starting from the geometry, a periodic structure was generated and the material constants were determined using...
Article
Polycarbonate thermoplastic materials have found their usage in many automotive interior type products (e.g. cluster instruments, Head-Up displays etc.), due to their visual aspects offered to the products and to the good mechanical properties possessed, especially in forms of short fiber reinforced composites. This paper presents the tensile behav...
Article
Foam-based composite structures are widely used in the field of construction market for roofing and closing walls. This paper presents a mechanical characterization of a lightweight sandwich panels with foam core. The faces of the panels are made of thin steel sheets, and for the core, closed-cell polyurethane foam with a density of 40 kg/m³ was us...
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Additive manufacturing (AM) is a broad definition of various techniques to produce layer-by-layer objects made of different materials. In this paper, a comprehensive review of laser-based technologies for polymers, including powder bed fusion processes [e.g. selective laser sintering (SLS)] and vat photopolymerisation [e.g. stereolithography (SLA)]...
Research
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THIS CERTIFICATE IS AWARDED TO E. Linul, D.A. Şerban, L. Marsavina and J. Kovacik FOR "Low-cycle fatigue behaviour of ductile closed-cell aluminium alloy foams", Fatigue & Fracture of Engineering Materials & Structures 2017; 40:4, p. 597-604
Article
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Magnesium alloys are widely used in automotive (steering wheel frames) and aerospace due to their lightweight, ductility, energy absorption and castability properties. Finite Element Analysis and design optimisation have driven the improvement of structural crashworthiness, stiffness, strength, durability, and NVH (noise vibration, harshness) perfo...
Article
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The paper presents mode I and II fracture toughness results for polylactic acid material obtained via fused deposition modeling. The tests were performed using Single Edge Notch Bend specimens loaded in four point bending: symmetric for mode I, asymmetric for mode II, respectively. The notch was inserted by 3D printing, and by milling, respectively...