The aim of this study was to compare the reduced stresses according to Huber’s hypothesis and the displacement pattern in the region of the facial skeleton using a tooth- or bone-borne appliance in surgically assisted rapid maxillary expansion (SARME). In the current literature, the lack of updated reports about biomechanical effects in bone-borne appliances used in SARME is noticeable. Finite element analysis (FEA) was used for this study. Six facial skeleton models were created, five with various variants of osteotomy and one without osteotomy. Two different appliances for maxillary expansion were used for each model. The three-dimensional (3D) model of the facial skeleton was created on the basis of spiral computed tomography (CT) scans of a 32-year-old patient with maxillary constriction. The finite element model was built using ANSYS 15.0 software, in which the computations were carried out. Stress distributions and displacement values along the 3D axes were found for each osteotomy variant with the expansion of the tooth- and the bone-borne devices at a level of 0.5 mm. The investigation showed that in the case of a full osteotomy of the maxilla, as described by Bell and Epker in 1976, the method of fixing the appliance for maxillary expansion had no impact on the distribution of the reduced stresses according to Huber’s hypothesis in the facial skeleton. In the case of the bone-borne appliance, the load on the teeth, which may lead to periodontal and orthodontic complications, was eliminated. In the case of a full osteotomy of the maxilla, displacements in the buccolingual direction for all the variables of the bone-borne appliance were slightly bigger than for the tooth-borne appliance.

PEEK is a thermoplastic polymer with halfcrystallic structure – the scientific name of this material is poly(oxy- 1,4-phenylene-oxy-1,4-phenylenecarbonyl-1,4-phenylene). It has a high melt and glass transition temperatures (Tm = 340 oC, Tg = 143 oC), high chemical resistance and is melt processable. Thus it has been used in a variety of structural and insulation applications. Nowadays, one of them is the biomedical application. The mechanical properties of PEEK have been extensively investigated in many research papers. However, there is not so high number of papers devoted to the fracture susceptibility of PEEK-material. Therefore, the the aim of this work is to present the results of studies on PEEK material with the use of fracture toughness test and digital image correlation. In order to conduct the tests, there were used two types of samples: SENB and CT. In comparison with other polymeric materials subjected to biomedical application, PEEK material presents relatively good fracture resistance with their biocompatibility.

The analysis aimed at studying stresses reduced according to Huber’s hypothesis and displacement patterns at selected sites of the facial skeleton using a tooth-borne appliance in surgically assisted rapid maxillary expansion. Five different variants of osteotomy of the midface and a variant without surgical intervention were compared to determine the best model for making an incision in the maxilla. The finite element analysis (FEA) was used for the study. Five osteotomy variants and a variant without osteotomy were modelled using a tooth-borne appliance on a facial skeleton model of a 23-year-old woman with skeletal malocclusion. The finite element mesh was constructed based on the geometry imported into the ANSYS 15.0 (Swanson Analysis System of USA) software, in which calculations were performed using the finite element analysis. Stress distributions and displacement patterns along the X, Y and Z axes are presented for each osteotomy variant with the expansion of the tooth-borne appliance at a level of 0.5 mm. As a result of the analysis it was found that osteotomy of the palatal suture in conjunction with Le Fort I osteotomy has the biggest impact on the course of maxillary expansion. If no osteotomy is performed, an increase in stresses reduced according to Huber occurs in the entire facial skeleton with a simultaneous absence of maxillary expansion.

Description of fatigue crack growth in steel structural components using energy approachInfluence of the microstructure on the FCGR AIP Conference Proceedings 1780, 050003 (2016) Abstract. In this paper, series of FEM analyses were performed to define stress intensity factors in 42CrMo4 steel lug joint and predict cycling crack growth. An eXtended Finite Element Method were used in computations to investigate influence of different types of boundary conditions. Crack geometry was assumed as through -thickness. The Results of stress intensity factors for stationary cracks were compared with Newman and Schijve analytical solutions. Crack paths were obtained for 2D by implementing Paris Law coupled with crack propagation criterion and direct cycling algorithm for three different hardness of steel (28,42,54 HRC). All the studies were computed an pre-processed in ABAQUS environment.