Product Reliability and NPD Implementation

#| '!! shinylive warning !!': |
#|   shinylive does not work in self-contained HTML documents.
#|   Please set `embed-resources: false` in your metadata.
#| standalone: true
#| viewerHeight: 800

library(shiny)

# ===================================================================
# UI
# ===================================================================
ui <- fluidPage(
  titlePanel("Weibull Theory"),
 
  sidebarLayout(
    sidebarPanel(
      h4("Weibull Parameters"),
      numericInput("beta", "Shape (β):", value = 1.5, min = 0.1, step = 0.1),
      numericInput("eta", "Scale (η):", value = 1.0, min = 0.1, step = 0.1),
      sliderInput("t", "Time t:", min = 1, max = 50, value = 1.0, step = 1)
    ),
   
    mainPanel(
      br(),
      plotOutput("weibullPlot", height = "400px"),
      fluidRow(
        column(4, strong("Time t ="), textOutput("t_val", inline = TRUE)),
        column(4, strong("S(t) ="), textOutput("S_val", inline = TRUE)),
        column(4, strong("h(t) ="), textOutput("h_val", inline = TRUE))
      ),
      fluidRow(
        column(6, strong("MTTF ="), textOutput("mttf_val", inline = TRUE)),
        column(6, strong("B10 ="), textOutput("b10_val", inline = TRUE))
      )
    )
  )
)
# ===================================================================
# SERVER
# ===================================================================
server <- function(input, output) {
 
  # -----------------------------------------------------------------
  # Theory Calculations
  # -----------------------------------------------------------------
  weibull_vals <- reactive({
    t <- input$t
    beta <- input$beta
    eta <- input$eta
    S <- pweibull(t, shape = beta, scale = eta, lower.tail = FALSE)
    h <- dweibull(t, shape = beta, scale = eta) / S
    mttf <- eta * gamma(1 + 1/beta)
    b10 <- qweibull(0.1, shape = beta, scale = eta)
    list(t = t, S = S, h = h, mttf = mttf, b10 = b10)
  })
 
  output$weibullPlot <- renderPlot({
    t <- input$t
    beta <- input$beta
    eta <- input$eta
    par(mar = c(5, 4, 4, 4) + 0.3)
   
    curve(pweibull(x, beta, eta, lower.tail = FALSE), from = 0.001, to = 50,
          col = "darkgreen", lwd = 3, ylim = c(0, 1), ylab = "Survival S(t)", xlab = "Time")
    par(new = TRUE)
    curve((beta/eta) * (x/eta)^(beta - 1), from = 0.001, to = 50,
          col = "purple", lwd = 3, axes = FALSE, xlab = "", ylab = "")
    axis(4, col = "purple", col.axis = "purple")
    mtext("Hazard h(t)", side = 4, line = 3, col = "purple")
    abline(v = t, col = "green", lwd = 2)
    grid()
    legend("topright", legend = c("S(t)", "h(t)"), col = c("darkgreen", "purple"), lwd = 3, bg="white")
  })
 
  output$t_val <- renderText(sprintf("%.4f", weibull_vals()$t))
  output$S_val <- renderText(sprintf("%.6f", weibull_vals()$S))
  output$h_val <- renderText(sprintf("%.6f", weibull_vals()$h))
  output$mttf_val <- renderText(sprintf("%.6f", weibull_vals()$mttf))
  output$b10_val <- renderText(sprintf("%.6f", weibull_vals()$b10))
}
shinyApp(ui, server)