Larissa Driemeier
University of São Paulo
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Featured researches published by Larissa Driemeier.
Dental Materials | 2010
B. Pick; J.B.C. Meira; Larissa Driemeier; Roberto R. Braga
OBJECTIVE To evaluate the biaxial and short-beam uniaxial strength tests applied to resin composites based upon their Weibull parameters, fractographic features and stress distribution. METHODS Disk- (15 mm x 1 mm) and beam-shaped specimens (10 mm x 2 mm x 1 mm) of three commercial composites (Concept/Vigodent, CA; Heliomolar/Ivoclar-Vivadent, HE; Z250/3M ESPE, FZ) were prepared. After 48h dry storage at 37 degrees C, disks and beams were submitted to piston-on-three-balls (BI) and three-point bending (UNI) tests, respectively. Data were analyzed by Weibull statistics. Fractured surfaces were observed under stereomicroscope and scanning electron microscope. Maximum principal stress (sigma(1)) distribution was determined by finite element analysis (FEA). Maximum sigma(1-BI) and sigma(1-UNI) were compared to FZ strengths calculated by applying the average failure loads to the analytical equations (sigma(a-BI) and sigma(a-UNI)). RESULTS For BI, characteristic strengths were: 169.9a (FZ), 122.4b (CA) and 104.8c (HE), and for UNI were: 160.3a (FZ), 98.2b (CA) and 91.6b (HE). Weibull moduli (m) were similar within the same test. CA and HE presented statistically higher m for BI. Surface pores (BI) and edge flaws (UNI) were the most frequent fracture origins. sigma(1-BI) was 14% lower than sigma(a-BI). sigma(1-UNI) was 43% higher than sigma(a-UNI). SIGNIFICANCE Compared to the short-beam uniaxial test, the biaxial test detected more differences among composites and displayed less data scattering for two of the tested materials. Also, biaxial strength was closer to the materials strength estimated by FEA.
Dental Traumatology | 2012
Neide Pena Coto; J.B.C. Meira; Reinaldo Brito e Dias; Larissa Driemeier; Guilherme de Oliveira Roveri; Pedro Yoshito Noritomi
There has been a significant increase in the number of facial fractures stemming from sport activities in recent years, with the nasal bone one of the most affected structures. Researchers recommend the use of a nose protector, but there is no standardization regarding the material employed. Clinical experience has demonstrated that a combination of a flexible and rigid layer of ethylene vinyl acetate (EVA) offers both comfort and safety to practitioners of sports. The aim of the present study was the investigation into the stresses generated by the impact of a rigid body on the nasal bone on models with and without an EVA protector. For such, finite element analysis was employed. A craniofacial model was constructed from images obtained through computed tomography. The nose protector was modeled with two layers of EVA (1 mm of rigid EVA over 2 mm of flexible EVA), following the geometry of the soft tissue. Finite element analysis was performed using the LS Dyna program. The bone and rigid EVA were represented as elastic linear material, whereas the soft tissues and flexible EVA were represented as hyperelastic material. The impact from a rigid sphere on the frontal region of the face was simulated with a constant velocity of 20 m s(-1) for 9.1 μs. The model without the protector served as the control. The distribution of maximal stress of the facial bones was recorded. The maximal stress on the nasal bone surpassed the breaking limit of 0.13-0.34 MPa on the model without a protector, while remaining below this limit on the model with the protector. Thus, the nose protector made from both flexible and rigid EVA proved effective at protecting the nasal bones under high-impact conditions.
International Journal of Crashworthiness | 2012
André Takashi Matsumoto; Larissa Driemeier; Marcílio Alves
Preformed structural reinforcements have shown good performance in crash tests, where the great advantage is their weight. These reinforcements are designed with the aim of increasing the rigidity of regions with large deformations, thus stabilising sections of the vehicle that work as load path during impact. The objective of this work is to show the application of structural reinforcements made of polymeric material PA66 in the field of vehicle safety, through finite element simulations. Simulations of frontal impact at 50 km/h and in ODB (offset deformable barrier) at 57 km/h configurations (standards such as ECE R-94 and ECE R-12) were performed in the software LS-DYNA® and MADYMO®. The simulations showed that the use of polymeric reinforcements leads to a 70% reduction in A-pillar intrusion, a 65% reduction in the displacement of the steering column and a 59% reduction in the deformation in the region of the occupant legs and feet. The level of occupant injuries was analysed by MADYMO® software, and a reduction of 23.5% in the chest compression and 80% in the tibia compression were verified. According to the standard, such conditions lead to an improvement in the occupant safety in a vehicle collision event.
Dental Traumatology | 2016
Ivan Onone Gialain; Neide Pena Coto; Larissa Driemeier; Pedro Yoshito Noritomi; Reinaldo Brito e Dias
BACKGROUND/AIM The aim of this study was to evaluate the compressive and tensile stresses on dentin and enamel in five different situations: no mouthguard and mouthguards from 1 mm thickness up to 4 mm thickness, using finite element analysis. MATERIALS AND METHODS A three-dimensional geometry of an upper right central incisor was obtained from a computed tomography and transformed into a mesh separating enamel from dentin. A mouthguard was created covering the buccal surface of the enamel in different thicknesses, and a rubber ball with a velocity of 5 m s(-1) was made as the impact object. RESULTS The maximum principal stress and the minimal principal stress were evaluated in all situations on dentin and enamel. Both maximum and minimal stress on enamel had the greatest value on the control situation (no mouthguard), and their value decreased as the mouthguard thickness increased. The reduction ranged from 66.62% to 85.5% for compressive stress and from 9.76% to 33.37% for tensile stress on enamel. The results for dentin were similar among the situations with or without mouthguards. CONCLUSION The mouthguard had beneficial effect considering the stresses on enamel, and between the mouthguard thickness of 3 and 4 mm, there was minimum difference.
International Journal of Crashworthiness | 2016
Larissa Driemeier; A. Yoneda; Rafael Traldi Moura; Marcílio Alves
Abstract The main function of a road guardrail is to redirect an out of control vehicle avoiding a frontal collision or a dangerous veering off the road trajectory. Second, the energy absorption imposed by barrier deformation or any other energy dissipation method is beneficial to the car occupant safety. This study evaluates the performance of a W-Beam guardrail system, in accordance to Brazilian Standards, in respect to the kinetic energy absorption and to the vehicle return angle to the road. This evaluation of the guardrails is performed in a virtual environment using the finite element method. For the correct representation of the model, the material was characterised through experimental tests. Simplifications in the model are taken from the literature and a validated model of a vehicle is provided by the US National Crash Analysis Center.
International Journal of Plasticity | 2008
Michael Brünig; Oliver Chyra; Daniel Albrecht; Larissa Driemeier; Marcílio Alves
Mechanics of Materials | 2010
Larissa Driemeier; Michael Brünig; Giancarlo Micheli; Marcílio Alves
International Journal of Plasticity | 2007
Michael Brünig; Larissa Driemeier
International Journal of Plasticity | 2015
Larissa Driemeier; Rafael Traldi Moura; Izabel Fernanda Machado; Marcílio Alves
Communications in Nonlinear Science and Numerical Simulation | 2005
Larissa Driemeier; Sergio Persival Baroncini Proença; Marcílio Alves