Análise termomecânica e probabilística de um pavimento de concreto em regime transiente modelado via método dos elementos finitos

O presente artigo apresenta um estudo estatístico e de sensibilidade de um pavimento de concreto submetido a um gradiente térmico em regime transiente. Dois modelos em 3D, um determinístico e outro probabilístico, são implementados no software ANSYS APDL, cuja base é o método dos elementos finitos, considerando-se a simetria geométrica e de carregamento termomecânico. O pavimento de concreto é composto por uma placa de concreto apoiada em uma base de concreto rolado e essa sob uma sub-base de poliuretano. Os elementos hexagonais Solid70 e Solid185 são utilizados na modelagem do pavimento, possuem respectivamente um grau de liberdade térmico e três graus de liberdade mecânicos por nó e um total de 8 nós. Incertezas na geometria e nas propriedades termomecânicas dos materiais constituintes do pavimento são inseridas nos modelos implementados utilizando a simulação de Monte Carlo, associada a amostragem por hipercubo latino. A análise de sensibilidade das variáveis de projeto também é realizada utilizando o coeficiente de correlação de Spearman. A distribuição das temperaturas sofridas pela placa de concreto utilizando o modelo determinístico foi comparada e validada de acordo com a literatura. O modelo probabilístico proposto permite demonstrar, de forma estatística, como as incertezas afetam as temperaturas e os valores máximos e mínimos para os deslocamentos verticais na placa de concreto. A análise de sensibilidade permitiu constatar a baixa significância da sub-base nas respostas mecânicas do pavimento. O modelo probabilístico também permite a obtenção das estatísticas e funções de distribuição acumulada de probabilidade das variáveis de saída da placa de concreto, que podem ser utilizadas no seu projeto.

Finite Element Models of a Benchmark Footbridge

Modern footbridges are often lively structures, characterized by natural frequencies that fall in the range of pedestrian activities, such as walking, running, and jumping. Therefore, serviceability assessment under human-induced excitation is crucial both at the design stage and during the footbridge lifetime. This paper presents and validates two different FE models of an existing footbridge with very complex geometry: the Streicker Footbridge at the Princeton University Campus. It represents a benchmark in the field as a testbed for vibration serviceability assessments under pedestrian excitation. The real structure is equipped with strain and temperature sensors that are currently used to collect measurements in both static and dynamic modes for research and educational purposes in Structural Health Monitoring (SHM). Based on detailed drawings of the Streicker Footbridge, a three-dimensional beam-based model was developed to represent the complex behavior of the full-scale benchmark bridge. Subsequently, a more refined discretization of the bridge deck adopting shell elements was inserted. The bridge Finite Element models were validated against available SHM data concerning static and dynamic tests. The relevant ANSYS APDL script files along with an example of pedestrian jumping application are available upon request for further research developments on the relationship between pedestrians and the benchmark footbridge.

Finite element modelling of moving loads on structures

This paper provides a breif description of the moving load problem (force or mass) across a structure. Development of a matlab script to solve the analytical equations of motion is provided. The method of implementation to solve this type of structural dynamics, using the Finite Element Method is then described with a matlab script for a simply supported beam provided. Additionally, a script and method for implementing the Finite Element Method using ANSYS APDL is also given.

Study of the influence of the foundation and the reservoir on the dynamic response in a concrete gravity dam profile

abstract: This work aims to verify the influence of the foundation and the reservoir on the dynamic behavior of concrete gravity dams in terms of the natural frequencies, vibration modes for a free vibration analysis; and in terms of maximum displacements and maximum stresses at singular points of the structure for a seismic excitation. The dam-reservoir-foundation interaction was investigated through modal and transient analysis by the finite element method via ANSYS APDL software. For this study, we used a typical Brazilian dam profile and compatible data from a Brazilian earthquake for the seismic excitation. The results showed the influence of the reservoir and the foundation on the natural frequencies in the coupled system, as well as its repercussions on the response of the dam under seismic excitation.

DESIGN, ANALYSIS AND COMPARISON OF VARIOUS MATERIALS FOR CONNECTING ROD

Connecting rod is engine component which transmits motion from piston to the crankshaft and serves as lever arm. The function of connecting rod is to convert piston’s reciprocal movement into rotary motion of the crankshaft. Connecting rod generally made from Carbon steel and Aluminium alloys have been used in recent days and some different materials are finding it’s application. The performance connecting rod in automobile engine is influenced by it’s design and weight for production of durable, cheaper and light connecting rod, hence optimization and analysis of connecting rod. The 3D model of connecting rod is designed and developed using CATIA V5. In proposed approach different materials compared like Aluminium alloy 7075, Magnesium alloy, Titanium alloys (Ti -3Al- 2.5V) and beryllium alloy (25) are taken for the analysis of connecting rod and factors like Stress, Strain and Deformation were obtained. The purpose of this study is identify best materials for connecting rod, after analysing at ANSYS APDL 15.0. KEYWORDS : Connecting rod, CATIA V5, ANSYS APDL15.0, Aluminium alloy 7075, Magnesium alloy, Titanium alloy (Ti-3Al-2.5V) and Beryllium Alloy (25).

Simulasi Pembebanan Pada Shackle Menggunakan Perangkat Lunak Ansys APDL 15.0

Berbagai jenis teknologi rekayasa dan simulasi telah banyak dikembangkan yang bertujuan untuk memudahkan pekerjaan manusia. Shackle adalah alat yang dipergunakan untuk mengangkat serta memindahkan suatu benda dari satu tempat ke tempat lainnya. Pada penelitian ini, akan dihitung distribusi tegangan yang terjadi pada shackle pada kondisi pengangkatan tangki minyak kapasitas 6 ton. Perhitungan dengan menggunakan prinsip metode elemen hingga dengan bantuan software Ansys APDL 15.0. Tujuan penelitian ini ialah: (1) mendesain bentuk shackle dan kondisi pembebanan, (2) simulasi distribusi tegangan pada pin dan struktur shackle, dan (3) analisa kegagalan bahan dengan menggunakan metode Tresca dan Energi Distorsi. Beban input berasal dari berat tangki yang akan digunakan dan berat bahan bakar yang disimpan dalam tangki. Metode analisis menggunakan MEH dengan jenis analisa structural den jenis elemen Beam 3Node 189. Berdasarkan hasil simulasi MEH, tegangan maksimum yang terjadi pada pin ialah 29,864 MPa dan defleksi maksimum ialah 0,0026 mm. Tegangan maksimum pada shackle ialah 76,02 MPa dan defleksi maksimum ialah 0,1881 mm. Berdasarkan teori Tresca dan Energi Distorsi, diperolah bahwa tegangan yang terjadi masih jahu dari kriteria kegagalan struktur. Demikian juga dengan defleksi yang terjadi sangat kecil sehingga shackle aman digunakan.