The concept of localization during the postpeak of compressive strain softening is presented. To explore localization in compression, a feedback-control method using a linear combination of displacement and force that partially subtracts the elastic response of the specimen to give a stable feedback signal is used. Results are presented from two test series (45 and 90 MPa) that use this method ...

OBJECTIVE To investigate the compressive force applied to the head during mask ventilation and determine whether this force increases in response to an attempt to correct the mask leak. METHODS The authors asked 24 participants (consultants, fellows and nurses) to administer positive pressure ventilation to a modified leak-free, term newborn manikin using a self-inflating bag (SIB) and a Neop...

Crumpled sheets have a surprisingly large resistance to further compression. We have studied the crumpling of thin sheets of Mylar under different loading conditions. When placed under a fixed compressive force, the size of a crumpled material decreases logarithmically in time for periods up to three weeks. We also find hysteretic behavior when measuring the compression as a function of applied...

BACKGROUND To determine the influence of lifting speed and type on peak and cumulative back compressive force (BCF) and shoulder moment (SM) loads during symmetric lifting. Another aim of the study was to compare static and dynamic lifting models. METHODS Ten male participants performed a floor-to-shoulder, floor-to-waist, and waist-to-shoulder lift at three different speeds [slow (0.34 m/s),...

The effect of simulated early weight bearing on both micromotion and pullout strength of uncemented distal femoral stems was evaluated in this study. The effect of stem endosteal contact and bone quality on implant pullout strength was also analyzed. A randomized matched-pair study was performed using 8 bilateral pairs of fresh human cadaveric femoral specimens. Each specimen pair was dual-ener...

BACKGROUND Compressive force across the growth plate may cause retardation and even arrest of physeal growth. The purpose of this study was to investigate histologic changes, metabolic changes in terms of glycosaminoglycan (GAG) concentration, and contrast-enhanced micro-computed tomography (CEMCT) findings of physeal cartilage in a rabbit model of physeal damage caused by excessive compression...

OBJECTIVE The aims of this study were to investigate mandibular deformation under clenching and to estimate its effect on the stability of orthodontic mini-implants (OMI). METHODS Three finite element models were constructed using computed tomography (CT) images of 3 adults with different mandibular plane angles (A, low; B, average; and C, high). An OMI was placed between #45 and #46 in each ...

PURPOSE The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns. MATERIALS AND METHODS Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental in...