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There has been a prevalence of long-distance running footwear incorporating carbon-fiber plates within their midsoles, effectively increasing their longitudinal bending stiffness (LBS). This modification of modern racing footwear has occurred concurrently with large improvements in running times (Bermon et al., 2021), putting into question how these footwear components affect performance (Muniz-Pardos et al., 2021). The current literature has investigated this at level running, but with the increasing popularity of trail running, it is of interest to investigate whether the benefits found during level running translate to graded running. Therefore, the overall aim of this study was to investigate the effects of increased footwear midsole longitudinal bending stiffness (i.e. carbon-fiber plates) on running energetics and biomechanics at various inclines. The effects of high LBS (Nike Vaporfly 4% with midsole intact) and low LBS (Nike Vaporfly 4% with mediolateral cuts made at the forefoot of the midsole through the carbon-fiber plate) footwear conditions were compared for running at 0°, 6°, and 12° inclines. Running energetics and biomechanics data were quantified by measuring metabolic rate and lower leg joint mechanics (from motion capture and ground reaction force measurements). Results from this study suggest that increasing longitudinal bending stiffness within the footwear midsoles has limited influence on running energetics (small non-significant improvements of metabolic power at all inclines), but has considerable effects on the biomechanics of the ankle and MTP joints. However, the most important between shoe differences were independent of grade, suggesting that the benefits of modern racing shoe observed for level running can be expected to translate to steep uphill running. Nevertheless, it should be noted that this study was only able to collect and use data for analysis from a limited number of participants (n=7), and therefore is underpowered, so there may be significant differences that go undetected

The use of timber in building structures is steadily increasing. cross laminated timber (CLT) is an engineered wood product made of an uneven number of layers of lamellas glued at an angle of 90 degrees to each other. This gives CLT high stiffness and strength to bending in all directions, and capability of taking load both in-plane and out-of-plane. Due to the large size of CLT elements, they allow for quick assembly of strong structures. Due to both economic and environmental reasons it is important for producers of CLT to optimize the use of the wood material by using the timber with higher stiffness and strength where it is most needed. This thesis is about evaluating the bending and shear stiffness of CLT elements, when used as plates, depending on the quality of wood used in the different layers. Four-point bending tests are carried out on elements of different compositions and a parametrized finite element model is created. Thus, the model is validated on the basis of experimental tests to evaluate the influence of different quality of different layers. The measured dynamic MoE proved to have good potential to be used as the longitudinal bending stiffness in an FE-model, with a deviation from the experimental tests of less than 1%. There is a strong correlation between the bending stiffness and bending strength of the plates. The effective rolling shear modulus in pine was calculated to be around 170 MPa for pine of dimension 40 x 195 mm2 . Grading the boards into two different classes used for different layers proved to increase the MoE of the plates by 11-17% for 3- and 5-layer CLT.

Cross-laminated timber (CLT) is an emerging sustainable engineered material with unique properties that in many ways make it superior to conventional construction material. CLT was invented in the 1990s and the volume produced have increased worldwide since then. It can be used in the load bearing structure for walls and floor slabs in the different typologies, e.g. residential and office buildings.The hygroscopic nature of wood allows it to exchange moisture with the surrounding environment. This may lead to an alteration of properties of wood-based materials such as CLT and can be accompanied by deformations and stresses. These effects influence the CLT’s structural stability, durability and safety.This study focuses on the consequences of moisture content variations in CLT structures, including mechanical properties like modulus of elasticity and bending stiffness (EI). Temperature and relative humidity were measured over three years in three positions along the thickness direction of a slab element on the first floor of House Charlie, a four-storey timber office building located in Växjö, Sweden.The investigation was carried out by mathematical modelling applying MATLAB® software aiming to find the moisture content as a function of time and thickness from the real-world data of House Charlie. The focus was on determining changes in modulus of elasticity and bending stiffness in response to moisture variation. The results showed that the moisture content within a slab of the building varied periodically following the seasonal variation throughout the years. The moisture content at the bottom of the slab was significantly lower compared to two other positions. According to the linear regression analysis, a linear relationship between the moisture content (MC) and positions across the CLT slab at each time step was defined. High R2 values, above 0.9, show the goodness of the fitted model. Applying the MC as a function of time and thickness into an available relationship of modulus of elasticity (E) could predict stiffness versus varied MC in the next step. The modulus of elasticity decreased with an increase in the moisture content over the studied period with a higher variation range at the bottom of the slab. In the final step, bending stiffness was assessed as a function of the changed moisture content. Bending stiffness increased periodically over time, attributed to overall more dry-out of the slab with time.The reported results of the present study give new insight into the behaviour of CLT structure over longer time periods. The recurring pattern in alterations stems from the reliance of bending stiffness on the modulus of elasticity function, which is in turn influenced by the linear relationship with moisture content exhibiting cyclic characteristics. The minimum and maximum values for EI were 3.5×1012 Nmm2 and 3.71×1012 Nmm2, respectively, a variation of approximately ±2.5% around the average. As the time steps increased, the bending stiffness also increased, given the progressive growth of the modulus of elasticity over time.

Mechanical Response Tissue Analysis (MRTA) is an emerging technology for assessing maximal bending stiffness (EI) of human long bones in vivo. The MRTA variable, EI, is the product of Young's modulus of elasticity (E) and cross-sectional moment of inertia (I). EI quantifies material and architectural/geometric properties of bone. Published human research using MRTA to measure EI has been limited to the ulna; however, the tibia requires further investigation due to its central involvement in many human activities and exercise-related clinical problems, e.g. stress fracture of the lower leg. To evaluate the inter- and intra-reliability of tibial EI, 22 healthy women (X + SD: 20.8 + 1.8 yr) were assessed twice daily for three non-consecutive days. Each daily session consisted of five repeated trials. The ulnar EI protocol of McCabe et al. [J Bone and Mineral Res. 1991;6(1):53-59] was adapted to assess tibial EI via MRTA. A significant difference was not found in scores for five repeated trials taken consecutively on the same day. Mean scores for EI were higher on day 1 (59.1 &#177; 35.5 N&#183;m², p < 0.05), compared to day 2 (46.9 &#177; 22.3) and day 3 (49.9 &#177; 18.3). Individual trial mean scores for EI on each day (mean of 5 trials) were highly correlated, R² = 0.84, 0.62, and 0.79 (set 1 vs. 2, for day 1,2,3, respectively) and the average percent change between sets 1 and 2 on each day was 5.3. The inter-test (between day) reproducibility was found to be low and unacceptable, 11.7, 18.3, and 1.3%, for day 1 vs. 2, 1 vs. 3, and 2 vs. 3. Poor inter-day reliability may be a result of the inability, at the time of this study, to apply the best computational EI model. It is concluded that tibial bone stiffness measurements with the MRTA are in the range of acceptability for same day inter- and intra-trial reliability when the 7-parameter analytic model of vibratory properties developed by McCabe et al. is used. / Master of Science

Bone mineral content (BMC) and bone mineral density (BMD), measured by dual x-ray absorptiometry are used clinically to diagnose osteoporosis and estimate risk for fragility fractures. Bone mineral explains up to 70% of bone strength; however, it does not take into account bone geometry. Mechanical Response Tissue Analysis is a method of non-invasively measuring the bending stiffness (EI) of bone which is determined by the product of Young's modulus of elasticity (E) and the areal cross sectional moment of inertia (I). The aim of the current study was to determine if high intensity strength training will increase ulnar bending stiffness in young women. Forty-nine women aged 19.9 ± 1.7 yrs, trained their nondominant arm either concentrically or eccentrically in the Isokinetic modality on the Biodex® system III 3d/wk for 32 wks. The dominant arm served as the control limb (untrained). Analysis of all subjects regardless of training mode demonstrated a significant increase in ulnar EI (22% ↑, P=0.01) with no significant difference in the untrained arm. When EI results were assessed by training mode, subjects who trained eccentrically showed a significant increase for ulnar EI in the trained limb (40% ↑, P=0.01) with no significant effect on the untrained limb while concentric training demonstrated no significant gain in either the trained or untrained arm. There was no effect of time x mode of training interaction for either the trained or untrained limb. Bone mineral density and bone mineral content of the ulna increased significantly in the trained arm in both concentric and eccentric training modes (P<0.05). These findings suggest support for the hypothesis that a critical threshold of mechanical bending loads may be necessary to effect an adaptation in bone strength and thus, eccentric training may be a novel approach to increase ulnar EI in young women. / Master of Science

No / This paper presents a series of test results of elliptical concrete filled steel tubular (CFST) beams and columns to explore their performance under bending and compression. A total of twenty-six specimens were tested, including eight beams under pure bending and eighteen columns under the combination of bending and compression. The main parameters were the shear span to depth ratio for beams, the slenderness ratio and the load eccentricity for columns. The test results showed that the CFST beams and columns with elliptical sections behaved in ductile manners and were similar to the CFST members with circular sections. Finally, simplified models for predicting the bending strength, the initial and serviceability-level section bending stiffness of the elliptical CFST beams, as well as the axial and eccentric compressive strength of the composite columns were discussed.

I samband med att intresset för att bygga högre trähus har ökat så krävs nya lösningar för att t.ex. kunna möta efterfrågan på stora öppna ytor och långa spännvidder. Träbjälklag med lång spännvidd har dock oftast svårigheter med att klara kraven på svikt och vibrationer. Ett nyutvecklat förslag på träbjälklag som förmodas klara dessa krav bättre än traditionella träbjälklag har varit utgångspunkten för detta examensarbete där syftet har varit att undersöka bjälklagets styvhet. Detta gjordes laborativt genom att bygga och testa en prototyp av det föreslagna bjälklaget och genom att en numerisk modell baserad på finita element metoden togs fram och användes för att studera hur olika parametrar påverkar bjälklagets styvhetsegenskaper. Bjälklagets design bygger på fackverksprincipen i primärriktningen och på balkverkan i sekundärriktningen. De ingående komponenterna har kommit prefabricerade till Växjö universitet där de har monterats ihop till ett fullskaligt bjälklagselement. Elementet har sedan utsatts för ett antal belastningsfall där nedböjningarna uppmätts vilka sedan givit underlag för att få värden på bjälklagets effektiva styvhetsegenskaper. Både de laborativa och de simulerade resultaten visar på en hög böjstyvhet i primärriktningen d.v.s. 18,9•106 Nm2/m [EI/b] respektive 18,6•106 Nm2/m [EI/b]. Även böjstyvheten i sekundärriktningen är hög d.v.s. motsvarar 21,2 % respektive 17,1 % av styvheten i primärriktningen. I beräkningsmodellen har det dessutom undersökts hur ett övre lager av spånskivor inverkar på bjälklagets styvhet. / The interest for building higher and larger wooden houses has increased in Sweden during the last decade resulting in higher requirements on the technical performance of such structures in order to met demands on large open surfaces and large spans of floors. Wooden floor systems with large spans often have difficulties, however, to meet the vibration requirements. A novel floor system, likely to handle the vibration requirements better than traditional wooden floor systems, is the basis for this master thesis. The purpose is to examine the stiffness of the floor by building and testing a prototype and by producing a numerical model based on the finite element method. In the longitudinal, main load-bearing direction the floor system works as a truss with flanges of longitudinal oriented timber members and web diagonals of transversely oriented members. In the transverse direction the web diagonals work as beams. The components were prefabricated elsewhere and assembled at Växjö University into a prototype. The prototype was then exposed to a number of different load cases. Deflections were measured and stiffness properties of the floor were derived. In addition to the experimental analysis the numerical model was used to calculate deflections when subjected to different load cases and for evaluating the principal stiffness properties of the floor. Both the experimental and the calculated results using the numerical model show high bending stiffness in the longitudinal direction, EI/b = 18,9•106 Nm2/m and 18,6•106 Nm2/m respectively. Also the bending stiffness in the transversal direction is high and equivalent to 21,2 % or 17,1 % (testing and simulation respectively) of the bending stiffness in the longitudinal direction. Using numerical analysis, also the effect on the stiffness of adding an upper layer of a 22 mm particleboard was examined.

<p>I samband med att intresset för att bygga högre trähus har ökat så krävs nya lösningar för att t.ex. kunna möta efterfrågan på stora öppna ytor och långa spännvidder. Träbjälklag med lång spännvidd har dock oftast svårigheter med att klara kraven på svikt och vibrationer. Ett nyutvecklat förslag på träbjälklag som förmodas klara dessa krav bättre än traditionella träbjälklag har varit utgångspunkten för detta examensarbete där syftet har varit att undersöka bjälklagets styvhet. Detta gjordes laborativt genom att bygga och testa en prototyp av det föreslagna bjälklaget och genom att en numerisk modell baserad på finita element metoden togs fram och användes för att studera hur olika parametrar påverkar bjälklagets styvhetsegenskaper.</p><p>Bjälklagets design bygger på fackverksprincipen i primärriktningen och på balkverkan i sekundärriktningen. De ingående komponenterna har kommit prefabricerade till Växjö universitet där de har monterats ihop till ett fullskaligt bjälklagselement. Elementet har sedan utsatts för ett antal belastningsfall där nedböjningarna uppmätts vilka sedan givit underlag för att få värden på bjälklagets effektiva styvhetsegenskaper.</p><p>Både de laborativa och de simulerade resultaten visar på en hög böjstyvhet i primärriktningen d.v.s. 18,9•106 Nm2/m [EI/b] respektive 18,6•106 Nm2/m [EI/b]. Även böjstyvheten i sekundärriktningen är hög d.v.s. motsvarar 21,2 % respektive 17,1 % av styvheten i primärriktningen.</p><p>I beräkningsmodellen har det dessutom undersökts hur ett övre lager av spånskivor inverkar på bjälklagets styvhet.</p> / <p>The interest for building higher and larger wooden houses has increased in Sweden during the last decade resulting in higher requirements on the technical performance of such structures in order to met demands on large open surfaces and large spans of floors. Wooden floor systems with large spans often have difficulties, however, to meet the vibration requirements. A novel floor system, likely to handle the vibration requirements better than traditional wooden floor systems, is the basis for this master thesis. The purpose is to examine the stiffness of the floor by building and testing a prototype and by producing a numerical model based on the finite element method.</p><p>In the longitudinal, main load-bearing direction the floor system works as a truss with flanges of longitudinal oriented timber members and web diagonals of transversely oriented members. In the transverse direction the web diagonals work as beams. The components were prefabricated elsewhere and assembled at Växjö University into a prototype. The prototype was then exposed to a number of different load cases. Deflections were measured and stiffness properties of the floor were derived. In addition to the experimental analysis the numerical model was used to calculate deflections when subjected to different load cases and for evaluating the principal stiffness properties of the floor.</p><p>Both the experimental and the calculated results using the numerical model show high bending stiffness in the longitudinal direction, EI/b = 18,9•106 Nm2/m and 18,6•106 Nm2/m respectively. Also the bending stiffness in the transversal direction is high and equivalent to 21,2 % or 17,1 % (testing and simulation respectively) of the bending stiffness in the longitudinal direction. Using numerical analysis, also the effect on the stiffness of adding an upper layer of a 22 mm particleboard was examined.</p>

Die exakte Kenntnis vom Materialverhalten und speziell von lokalen Flächenmasseschwankungen der textilen Flächen ist Voraussetzung für eine Verbesserung der Produktentwicklung und für eine hohe Qualitätsverarbeitung in der Konfektionsindustrie. Dieser Fakt ist ebenfalls für die zunehmende Anwendung im Bereich der Simulationsberechnungen von erheblicher Bedeutung. Der Wandel von 2D-CAD- zu 3D-CAD-Systemen führt in der Bekleidungsindustrie zur zwingenden Berücksichtigung der Materialeigenschaften. Aufgrund des Montageprozesses zeigen die konfektionierten textilen Flächen im Vergleich zu unkonfektionierten textilen Flächen ein anderes Erscheinungsbild. Mehrlagige Gewebe (infolge einer Naht, einer Einlage oder eines Futterstoffes) beeinflussen das Biegeverhalten und das Fallverhalten der textilen Flächen erheblich. Zur Bestimmung der Biegesteifigkeit ist seit Jahrzehnten das manuell zu bedienende Prüfgerät nach dem Cantilever-Verfahren das Bekannteste. Die eigenen Untersuchungen bestätigen, dass das Prüfgerät viele Mängel hat, welche die Genauigkeit und die Reproduzierbarkeit der Messergebnisse wesentlich beeinflussen. Im Rahmen dieser Arbeit wird ein neues Biegesteifigkeitsprüfgerät (ACPM 200) entwickelt, um eine optimale Genauigkeit und hohe Reproduzierbarkeit der Messergebnisse zu erfassen. Eine neue Methode zur Ermittlung des Einflusses der Naht auf die Biegesteifigkeit einer größeren textilen Fläche ist in der Arbeit vorhanden, um die exakte Beschreibung des realen Verhaltens von textilen Bekleidungsprodukten zu ermitteln. Die Simulation des Biegeverhaltens textiler Flächen ohne und mit vertikaler Naht wird mit Hilfe der FEM durchgeführt. Abschließend wird eine neue Prüfnorm vorgestellt, welche die Biegesteifigkeit von textilen Flächen mit lokalen Flächenmasseschwankungen mittels des neuen Biegesteifigkeitsprüfgerätes ACPM 200 beinhaltet. / Bending stiffness and Drapeability are essential material parameters for simulating textile and clothing products. Due to assembling processes garments are showing different appearances through modelling than textile fabrics. This is based on stiffening, which is caused by assembling process and local variations within material’s mass throughout the fabric. Since decades the manual bending stiffness testing device, which is based on Cantilever method, has been known. This device is insufficient because of irregular feed speed of bending sample, the visual determination of reaching and reading the bending length, the little reading precision of the measurable slide (half Millimetre) and the form of the front edge of the sample does not stay linear. Obtaining an exact evaluation of this sample edge is not possible with this device. Extensive experiments have confirmed that these deficits influence the accuracy and the reproduction of the results in a high degree. To remedy these deficits and to obtain an exact description of the material’s behaviour in order to achieve an optimal modelling of the clothing products is the new bending stiffness testing device (ACPM 200) at the ITB of TU Dresden developed. Within the investigations a new method for determining the influence of the seam on the bending stiffness of the adjacent textile fabric will be introduced. The Influence of seams on the drapability of textile fabric is investigated. A static model of Fabric with and without vertical seams is analysed with using the finite element method (FEM).